[PATCH v4 02/16] clk: tegra: Add library for the DFLL clock source (open-loop mode)
David Riley
davidriley at google.com
Wed Aug 27 22:58:10 PDT 2014
Hi Tuomas,
A bunch of small nit picks from me.
On Wed, Aug 20, 2014 at 2:04 PM, Tuomas Tynkkynen <ttynkkynen at nvidia.com> wrote:
> Add shared code to support the Tegra DFLL clocksource in open-loop
> mode. This root clocksource is present on the Tegra124 SoCs. The
> DFLL is the intended primary clock source for the fast CPU cluster.
>
> This code is very closely based on a patch by Paul Walmsley from
> December (http://comments.gmane.org/gmane.linux.ports.tegra/15273),
> which in turn comes from the internal driver by originally created
> by Aleksandr Frid <afrid at nvidia.com>.
>
> Subsequent patches will add support for closed loop mode and drivers
> for the Tegra124 fast CPU cluster DFLL devices, which rely on this
> code.
>
> Signed-off-by: Paul Walmsley <pwalmsley at nvidia.com>
> Signed-off-by: Tuomas Tynkkynen <ttynkkynen at nvidia.com>
> ---
> v4: Use correct accessor function for the DFLL_OUTPUT_CFG register
> v3: Fix incorrect order of arguments to dfll_scale_dvco_rate call
> ---
> drivers/clk/tegra/Makefile | 1 +
> drivers/clk/tegra/clk-dfll.c | 1090 ++++++++++++++++++++++++++++++++++++++++++
> drivers/clk/tegra/clk-dfll.h | 55 +++
> 3 files changed, 1146 insertions(+)
> create mode 100644 drivers/clk/tegra/clk-dfll.c
> create mode 100644 drivers/clk/tegra/clk-dfll.h
>
> diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
> index f7dfb72..47320ca 100644
> --- a/drivers/clk/tegra/Makefile
> +++ b/drivers/clk/tegra/Makefile
> @@ -1,5 +1,6 @@
> obj-y += clk.o
> obj-y += clk-audio-sync.o
> +obj-y += clk-dfll.o
> obj-y += clk-divider.o
> obj-y += clk-periph.o
> obj-y += clk-periph-gate.o
> diff --git a/drivers/clk/tegra/clk-dfll.c b/drivers/clk/tegra/clk-dfll.c
> new file mode 100644
> index 0000000..fb21018
> --- /dev/null
> +++ b/drivers/clk/tegra/clk-dfll.c
> @@ -0,0 +1,1090 @@
> +/*
> + * clk-dfll.c - Tegra DFLL clock source common code
> + *
> + * Copyright (C) 2012-2014 NVIDIA Corporation. All rights reserved.
> + *
> + * Aleksandr Frid <afrid at nvidia.com>
> + * Paul Walmsley <pwalmsley at nvidia.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * This library is for the DVCO and DFLL IP blocks on the Tegra124
> + * SoC. These IP blocks together are also known at NVIDIA as
> + * "CL-DVFS". To try to avoid confusion, this code refers to them
> + * collectively as the "DFLL."
> + *
> + * The DFLL is a root clocksource which tolerates some amount of
> + * supply voltage noise. Tegra124 uses it to clock the fast CPU
> + * complex when the target CPU speed is above a particular rate. The
> + * DFLL can be operated in either open-loop mode or closed-loop mode.
> + * In open-loop mode, the DFLL generates an output clock appropriate
> + * to the supply voltage. In closed-loop mode, when configured with a
> + * target frequency, the DFLL minimizes supply voltage while
> + * delivering an average frequency equal to the target.
> + *
> + * Devices clocked by the DFLL must be able to tolerate frequency
> + * variation. In the case of the CPU, it's important to note that the
> + * CPU cycle time will vary. This has implications for
> + * performance-measurement code and any code that relies on the CPU
> + * cycle time to delay for a certain length of time.
> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/debugfs.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pm_opp.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/seq_file.h>
> +
> +#include "clk-dfll.h"
> +
> +/*
> + * DFLL control registers - access via dfll_{readl,writel}
> + */
> +
> +/* DFLL_CTRL: DFLL control register */
> +#define DFLL_CTRL 0x00
> +#define DFLL_CTRL_MODE_MASK 0x03
> +
> +/* DFLL_CONFIG: DFLL sample rate control */
> +#define DFLL_CONFIG 0x04
> +#define DFLL_CONFIG_DIV_MASK 0xff
> +#define DFLL_CONFIG_DIV_PRESCALE 32
> +
> +/* DFLL_PARAMS: tuning coefficients for closed loop integrator */
> +#define DFLL_PARAMS 0x08
> +#define DFLL_PARAMS_CG_SCALE (0x1 << 24)
> +#define DFLL_PARAMS_FORCE_MODE_SHIFT 22
> +#define DFLL_PARAMS_FORCE_MODE_MASK (0x3 << DFLL_PARAMS_FORCE_MODE_SHIFT)
> +#define DFLL_PARAMS_CF_PARAM_SHIFT 16
> +#define DFLL_PARAMS_CF_PARAM_MASK (0x3f << DFLL_PARAMS_CF_PARAM_SHIFT)
> +#define DFLL_PARAMS_CI_PARAM_SHIFT 8
> +#define DFLL_PARAMS_CI_PARAM_MASK (0x7 << DFLL_PARAMS_CI_PARAM_SHIFT)
> +#define DFLL_PARAMS_CG_PARAM_SHIFT 0
> +#define DFLL_PARAMS_CG_PARAM_MASK (0xff << DFLL_PARAMS_CG_PARAM_SHIFT)
> +
> +/* DFLL_TUNE0: delay line configuration register 0 */
> +#define DFLL_TUNE0 0x0c
> +
> +/* DFLL_TUNE1: delay line configuration register 1 */
> +#define DFLL_TUNE1 0x10
> +
> +/* DFLL_FREQ_REQ: target DFLL frequency control */
> +#define DFLL_FREQ_REQ 0x14
> +#define DFLL_FREQ_REQ_FORCE_ENABLE (0x1 << 28)
> +#define DFLL_FREQ_REQ_FORCE_SHIFT 16
> +#define DFLL_FREQ_REQ_FORCE_MASK (0xfff << DFLL_FREQ_REQ_FORCE_SHIFT)
> +#define FORCE_MAX 2047
> +#define FORCE_MIN -2048
> +#define DFLL_FREQ_REQ_SCALE_SHIFT 8
> +#define DFLL_FREQ_REQ_SCALE_MASK (0xff << DFLL_FREQ_REQ_SCALE_SHIFT)
> +#define DFLL_FREQ_REQ_SCALE_MAX 256
> +#define DFLL_FREQ_REQ_FREQ_VALID (0x1 << 7)
> +#define DFLL_FREQ_REQ_MULT_SHIFT 0
> +#define DFLL_FREQ_REG_MULT_MASK (0x7f << DFLL_FREQ_REQ_MULT_SHIFT)
> +#define FREQ_MAX 127
> +
> +/* DFLL_DROOP_CTRL: droop prevention control */
> +#define DFLL_DROOP_CTRL 0x1c
> +
> +/* DFLL_OUTPUT_CFG: closed loop mode control registers */
> +/* NOTE: access via dfll_i2c_{readl,writel} */
> +#define DFLL_OUTPUT_CFG 0x20
Missing a tab?
> +#define DFLL_OUTPUT_CFG_I2C_ENABLE (0x1 << 30)
> +#define OUT_MASK 0x3f
> +#define DFLL_OUTPUT_CFG_SAFE_SHIFT 24
> +#define DFLL_OUTPUT_CFG_SAFE_MASK \
> + (OUT_MASK << DFLL_OUTPUT_CFG_SAFE_SHIFT)
> +#define DFLL_OUTPUT_CFG_MAX_SHIFT 16
> +#define DFLL_OUTPUT_CFG_MAX_MASK \
> + (OUT_MASK << DFLL_OUTPUT_CFG_MAX_SHIFT)
> +#define DFLL_OUTPUT_CFG_MIN_SHIFT 8
> +#define DFLL_OUTPUT_CFG_MIN_MASK \
> + (OUT_MASK << DFLL_OUTPUT_CFG_MIN_SHIFT)
> +#define DFLL_OUTPUT_CFG_PWM_DELTA (0x1 << 7)
> +#define DFLL_OUTPUT_CFG_PWM_ENABLE (0x1 << 6)
> +#define DFLL_OUTPUT_CFG_PWM_DIV_SHIFT 0
> +#define DFLL_OUTPUT_CFG_PWM_DIV_MASK \
> + (OUT_MASK << DFLL_OUTPUT_CFG_PWM_DIV_SHIFT)
> +
> +/* DFLL_OUTPUT_FORCE: closed loop mode voltage forcing control */
> +#define DFLL_OUTPUT_FORCE 0x24
> +#define DFLL_OUTPUT_FORCE_ENABLE (0x1 << 6)
> +#define DFLL_OUTPUT_FORCE_VALUE_SHIFT 0
> +#define DFLL_OUTPUT_FORCE_VALUE_MASK \
> + (OUT_MASK << DFLL_OUTPUT_FORCE_VALUE_SHIFT)
> +
> +/* DFLL_MONITOR_CTRL: internal monitor data source control */
> +#define DFLL_MONITOR_CTRL 0x28
> +#define DFLL_MONITOR_CTRL_FREQ 6
> +
> +/* DFLL_MONITOR_DATA: internal monitor data output */
> +#define DFLL_MONITOR_DATA 0x2c
> +#define DFLL_MONITOR_DATA_NEW_MASK (0x1 << 16)
> +#define DFLL_MONITOR_DATA_VAL_SHIFT 0
> +#define DFLL_MONITOR_DATA_VAL_MASK (0xFFFF << DFLL_MONITOR_DATA_VAL_SHIFT)
> +
> +/*
> + * I2C output control registers - access via dfll_i2c_{readl,writel}
> + */
> +
> +/* DFLL_I2C_CFG: I2C controller configuration register */
> +#define DFLL_I2C_CFG 0x40
> +#define DFLL_I2C_CFG_ARB_ENABLE (0x1 << 20)
> +#define DFLL_I2C_CFG_HS_CODE_SHIFT 16
> +#define DFLL_I2C_CFG_HS_CODE_MASK (0x7 << DFLL_I2C_CFG_HS_CODE_SHIFT)
> +#define DFLL_I2C_CFG_PACKET_ENABLE (0x1 << 15)
> +#define DFLL_I2C_CFG_SIZE_SHIFT 12
> +#define DFLL_I2C_CFG_SIZE_MASK (0x7 << DFLL_I2C_CFG_SIZE_SHIFT)
> +#define DFLL_I2C_CFG_SLAVE_ADDR_10 (0x1 << 10)
> +#define DFLL_I2C_CFG_SLAVE_ADDR_SHIFT_7BIT 1
> +#define DFLL_I2C_CFG_SLAVE_ADDR_SHIFT_10BIT 0
> +#define DFLL_I2C_CFG_SLAVE_ADDR_MASK (0x3ff << DFLL_I2C_CFG_SLAVE_ADDR_SHIFT)
DFLL_I2C_CFG_SLAVE_ADDR_SHIFT isn't defined, and
DFLL_I2C_CFG_SLAVE_ADDR_MASK does the wrong thing for 7-bit shift.
> +
> +/* DFLL_I2C_VDD_REG_ADDR: PMIC I2C address for closed loop mode */
> +#define DFLL_I2C_VDD_REG_ADDR 0x44
Missing a tab? I think some of the above section also might not be
lined up with the rest.
> +
> +/* DFLL_I2C_STS: I2C controller status */
> +#define DFLL_I2C_STS 0x48
> +#define DFLL_I2C_STS_I2C_LAST_SHIFT 1
> +#define DFLL_I2C_STS_I2C_REQ_PENDING 0x1
> +
> +/* DFLL_INTR_STS: DFLL interrupt status register */
> +#define DFLL_INTR_STS 0x5c
> +
> +/* DFLL_INTR_EN: DFLL interrupt enable register */
> +#define DFLL_INTR_EN 0x60
> +#define DFLL_INTR_MIN_MASK 0x1
> +#define DFLL_INTR_MAX_MASK 0x2
> +
> +/*
> + * Integrated I2C controller registers - relative to td->i2c_controller_base
> + */
> +
> +/* DFLL_I2C_CLK_DIVISOR: I2C controller clock divisor */
> +#define DFLL_I2C_CLK_DIVISOR 0x6c
> +#define DFLL_I2C_CLK_DIVISOR_MASK 0xffff
> +#define DFLL_I2C_CLK_DIVISOR_FS_SHIFT 16
> +#define DFLL_I2C_CLK_DIVISOR_HS_SHIFT 0
> +#define DFLL_I2C_CLK_DIVISOR_PREDIV 8
> +#define DFLL_I2C_CLK_DIVISOR_HSMODE_PREDIV 12
> +
> +/*
> + * Other constants
> + */
> +
> +/* MAX_DFLL_VOLTAGES: number of LUT entries in the DFLL IP block */
> +#define MAX_DFLL_VOLTAGES 33
> +
> +/*
> + * REF_CLK_CYC_PER_DVCO_SAMPLE: the number of ref_clk cycles that the hardware
> + * integrates the DVCO counter over - used for debug rate monitoring and
> + * droop control
> + */
> +#define REF_CLK_CYC_PER_DVCO_SAMPLE 4
> +
> +/*
> + * REF_CLOCK_RATE: the DFLL reference clock rate currently supported by this
> + * driver, in Hz
> + */
> +#define REF_CLOCK_RATE 51000000UL
> +
> +
> +/**
> + * enum dfll_ctrl_mode - DFLL hardware operating mode
> + * @DFLL_UNINITIALIZED: (uninitialized state - not in hardware bitfield)
> + * @DFLL_DISABLED: DFLL not generating an output clock
> + * @DFLL_OPEN_LOOP: DVCO running, but DFLL not adjusting voltage
> + *
> + * The integer corresponding to the last two states, minus one, is
> + * written to the DFLL hardware to change operating modes.
> + */
> +enum dfll_ctrl_mode {
> + DFLL_UNINITIALIZED = 0,
> + DFLL_DISABLED = 1,
> + DFLL_OPEN_LOOP = 2,
> +};
> +
> +/**
> + * enum dfll_tune_range - voltage range that the driver believes it's in
> + * @DFLL_TUNE_UNINITIALIZED: DFLL tuning not yet programmed
> + * @DFLL_TUNE_LOW: DFLL in the low-voltage range (or open-loop mode)
> + *
> + * Some DFLL tuning parameters may need to change depending on the
> + * DVCO's voltage; these states represent the ranges that the driver
> + * supports. These are software states; these values are never
> + * written into registers.
> + */
> +enum dfll_tune_range {
> + DFLL_TUNE_UNINITIALIZED = 0,
> + DFLL_TUNE_LOW = 1,
> +};
> +
> +struct tegra_dfll {
> + struct device *dev;
> + struct tegra_dfll_soc_data *soc;
> +
> + void __iomem *base;
> + void __iomem *i2c_base;
> + void __iomem *i2c_controller_base;
> + void __iomem *lut_base;
> +
> + struct regulator *vdd_reg;
> + struct clk *soc_clk;
> + struct clk *ref_clk;
> + struct clk *i2c_clk;
> + struct clk *dfll_clk;
> + unsigned long ref_rate;
> + unsigned long i2c_clk_rate;
> + unsigned long dvco_rate_min;
> +
> + enum dfll_ctrl_mode mode;
> + enum dfll_tune_range tune_range;
> + struct dentry *debugfs_dir;
> + struct clk_hw dfll_clk_hw;
> + const char *output_clock_name;
> +
> + /* Parameters from DT */
> + u32 droop_ctrl;
> +};
> +
> +#define clk_hw_to_dfll(_hw) container_of(_hw, struct tegra_dfll, dfll_clk_hw)
> +
> +/* mode_name: map numeric DFLL modes to names for friendly console messages */
> +static const char * const mode_name[] = {
> + [DFLL_UNINITIALIZED] = "uninitialized",
> + [DFLL_DISABLED] = "disabled",
> + [DFLL_OPEN_LOOP] = "open_loop",
> +};
> +
> +/*
> + * Register accessors
> + */
> +
> +static inline u32 dfll_readl(struct tegra_dfll *td, u32 offs)
> +{
> + return __raw_readl(td->base + offs);
> +}
> +
> +static inline void dfll_writel(struct tegra_dfll *td, u32 val, u32 offs)
> +{
> + WARN_ON(offs >= DFLL_I2C_CFG);
> + __raw_writel(val, td->base + offs);
> +}
> +
> +static inline void dfll_wmb(struct tegra_dfll *td)
> +{
> + dfll_readl(td, DFLL_CTRL);
> +}
> +
> +/* I2C output control registers - for addresses above DFLL_I2C_CFG */
> +
> +static inline u32 dfll_i2c_readl(struct tegra_dfll *td, u32 offs)
> +{
> + return __raw_readl(td->i2c_base + offs);
> +}
> +
> +static inline void dfll_i2c_writel(struct tegra_dfll *td, u32 val, u32 offs)
> +{
> + __raw_writel(val, td->i2c_base + offs);
> +}
> +
> +static inline void dfll_i2c_wmb(struct tegra_dfll *td)
> +{
> + dfll_i2c_readl(td, DFLL_I2C_CFG);
> +}
> +
> +/**
> + * dfll_is_running - is the DFLL currently generating a clock?
> + * @td: DFLL instance
> + *
> + * If the DFLL is currently generating an output clock signal, return
> + * true; otherwise return false.
> + */
> +static bool dfll_is_running(struct tegra_dfll *td)
> +{
> + return td->mode >= DFLL_OPEN_LOOP;
> +}
> +
> +/*
> + * Runtime PM suspend/resume callbacks
> + */
> +
> +/**
> + * tegra_dfll_runtime_resume - enable all clocks needed by the DFLL
> + * @dev: DFLL device *
> + *
> + * Enable all clocks needed by the DFLL. Assumes that clk_prepare()
> + * has already been called on all the clocks.
> + *
> + * XXX Should also handle context restore when returning from off.
> + */
> +int tegra_dfll_runtime_resume(struct device *dev)
> +{
> + struct tegra_dfll *td = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = clk_enable(td->i2c_clk);
> + if (ret) {
> + dev_err(dev, "could not enable I2C clock: %d\n", ret);
> + return ret;
> + }
> +
> + ret = clk_enable(td->ref_clk);
> + if (ret) {
> + dev_err(dev, "could not enable ref clock: %d\n", ret);
> + return ret;
> + }
> +
> + ret = clk_enable(td->soc_clk);
> + if (ret) {
> + dev_err(dev, "could not enable register clock: %d\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(tegra_dfll_runtime_resume);
> +
> +/**
> + * tegra_dfll_runtime_suspend - disable all clocks needed by the DFLL
> + * @dev: DFLL device *
> + *
> + * Disable all clocks needed by the DFLL. Assumes that other code
> + * will later call clk_unprepare().
> + */
> +int tegra_dfll_runtime_suspend(struct device *dev)
> +{
> + struct tegra_dfll *td = dev_get_drvdata(dev);
> +
> + clk_disable(td->soc_clk);
> + clk_disable(td->ref_clk);
> + clk_disable(td->i2c_clk);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(tegra_dfll_runtime_suspend);
> +
> +/*
> + * DFLL tuning operations (per-voltage-range tuning settings)
> + */
> +
> +/**
> + * dfll_tune_low - tune to DFLL and CPU settings valid for any voltage
> + * @td: DFLL instance
> + *
> + * Tune the DFLL oscillator parameters and the CPU clock shaper for
> + * the low-voltage range. These settings are valid for any voltage,
> + * but may not be optimal.
> + */
> +static void dfll_tune_low(struct tegra_dfll *td)
> +{
> + td->tune_range = DFLL_TUNE_LOW;
> +
> + dfll_writel(td, td->soc->tune0_low, DFLL_TUNE0);
> + dfll_writel(td, td->soc->tune1, DFLL_TUNE1);
> + dfll_wmb(td);
> +
> + if (td->soc->set_clock_trimmers_low)
> + td->soc->set_clock_trimmers_low();
> +}
> +
> +/*
> + * Output clock scaler helpers
> + */
> +
> +/**
> + * dfll_scale_dvco_rate - calculate scaled rate from the DVCO rate
> + * @scale_bits: clock scaler value (bits in the DFLL_FREQ_REQ_SCALE field)
> + * @dvco_rate: the DVCO rate
> + *
> + * Apply the same scaling formula that the DFLL hardware uses to scale
> + * the DVCO rate.
> + */
> +static unsigned long dfll_scale_dvco_rate(int scale_bits,
> + unsigned long dvco_rate)
> +{
> + return (u64)dvco_rate * (scale_bits + 1) / DFLL_FREQ_REQ_SCALE_MAX;
> +}
> +
> +/*
> + * Monitor control
> + */
> +
> +/**
> + * dfll_calc_monitored_rate - convert DFLL_MONITOR_DATA_VAL rate into real freq
> + * @monitor_data: value read from the DFLL_MONITOR_DATA_VAL bitfield
> + * @ref_rate: DFLL reference clock rate
> + *
> + * Convert @monitor_data from DFLL_MONITOR_DATA_VAL units into cycles
> + * per second. Returns the converted value.
> + */
> +static u64 dfll_calc_monitored_rate(u32 monitor_data,
> + unsigned long ref_rate)
> +{
> + return monitor_data * (ref_rate / REF_CLK_CYC_PER_DVCO_SAMPLE);
> +}
> +
> +/**
> + * dfll_read_monitor_rate - return the DFLL's output rate from internal monitor
> + * @td: DFLL instance
> + *
> + * If the DFLL is enabled, return the last rate reported by the DFLL's
> + * internal monitoring hardware. This works in both open-loop and
> + * closed-loop mode, and takes the output scaler setting into account.
> + * Assumes that the monitor was programmed to monitor frequency before
> + * the sample period started. If the driver believes that the DFLL is
> + * currently uninitialized or disabled, it will return 0, since
> + * otherwise the DFLL monitor data register will return the last
> + * measured rate from when the DFLL was active.
> + */
> +static u64 dfll_read_monitor_rate(struct tegra_dfll *td)
> +{
> + u32 v, s;
> + u64 pre_scaler_rate, post_scaler_rate;
> +
> + if (!dfll_is_running(td))
> + return 0;
> +
> + v = dfll_readl(td, DFLL_MONITOR_DATA);
> + v = (v & DFLL_MONITOR_DATA_VAL_MASK) >> DFLL_MONITOR_DATA_VAL_SHIFT;
> + pre_scaler_rate = dfll_calc_monitored_rate(v, td->ref_rate);
> +
> + s = dfll_readl(td, DFLL_FREQ_REQ);
> + s = (s & DFLL_FREQ_REQ_SCALE_MASK) >> DFLL_FREQ_REQ_SCALE_SHIFT;
> + post_scaler_rate = dfll_scale_dvco_rate(s, pre_scaler_rate);
> +
> + return post_scaler_rate;
> +}
> +
> +/*
> + * DFLL mode switching
> + */
> +
> +/**
> + * dfll_set_mode - change the DFLL control mode
> + * @td: DFLL instance
> + * @mode: DFLL control mode (see enum dfll_ctrl_mode)
> + *
> + * Change the DFLL's operating mode between disabled, open-loop mode,
> + * and closed-loop mode, or vice versa.
> + */
> +static void dfll_set_mode(struct tegra_dfll *td,
> + enum dfll_ctrl_mode mode)
> +{
> + td->mode = mode;
> + dfll_writel(td, mode - 1, DFLL_CTRL);
> + dfll_wmb(td);
> +}
> +
> +/*
> + * DFLL enable/disable & open-loop <-> closed-loop transitions
> + */
> +
> +/**
> + * dfll_disable - switch from open-loop mode to disabled mode
> + * @td: DFLL instance
> + *
> + * Switch from OPEN_LOOP state to DISABLED state. Returns 0 upon success
> + * or -EPERM if the DFLL is not currently in open-loop mode.
> + */
> +static int dfll_disable(struct tegra_dfll *td)
> +{
> + if (td->mode != DFLL_OPEN_LOOP) {
> + dev_err(td->dev, "cannot disable DFLL in %s mode\n",
> + mode_name[td->mode]);
> + return -EINVAL;
> + }
> +
> + dfll_set_mode(td, DFLL_DISABLED);
> + pm_runtime_put_sync(td->dev);
> +
> + return 0;
> +}
> +
> +/**
> + * dfll_enable - switch a disabled DFLL to open-loop mode
> + * @td: DFLL instance
> + *
> + * Switch from DISABLED state to OPEN_LOOP state. Returns 0 upon success
> + * or -EPERM if the DFLL is not currently disabled.
> + */
> +static int dfll_enable(struct tegra_dfll *td)
> +{
> + if (td->mode != DFLL_DISABLED) {
> + dev_err(td->dev, "cannot enable DFLL in %s mode\n",
> + mode_name[td->mode]);
> + return -EPERM;
> + }
> +
> + pm_runtime_get_sync(td->dev);
> + dfll_set_mode(td, DFLL_OPEN_LOOP);
> +
> + return 0;
> +}
> +
> +/**
> + * dfll_set_open_loop_config - prepare to switch to open-loop mode
> + * @td: DFLL instance
> + *
> + * Prepare to switch the DFLL to open-loop mode. This switches the
> + * DFLL to the low-voltage tuning range, ensures that I2C output
> + * forcing is disabled, and disables the output clock rate scaler.
> + * The DFLL's low-voltage tuning range parameters must be
> + * characterized to keep the downstream device stable at any DVCO
> + * input voltage. No return value.
> + */
> +static void dfll_set_open_loop_config(struct tegra_dfll *td)
> +{
> + u32 val;
> +
> + /* always tune low (safe) in open loop */
> + if (td->tune_range != DFLL_TUNE_LOW)
> + dfll_tune_low(td);
> +
> + val = dfll_readl(td, DFLL_FREQ_REQ);
> + val |= DFLL_FREQ_REQ_SCALE_MASK;
> + val &= ~DFLL_FREQ_REQ_FORCE_ENABLE;
> + dfll_writel(td, val, DFLL_FREQ_REQ);
> + dfll_wmb(td);
> +}
> +
> +/*
> + * Clock framework integration
> + */
> +
> +static int dfll_clk_is_enabled(struct clk_hw *hw)
> +{
> + struct tegra_dfll *td = clk_hw_to_dfll(hw);
> +
> + return dfll_is_running(td);
> +}
> +
> +static int dfll_clk_enable(struct clk_hw *hw)
> +{
> + struct tegra_dfll *td = clk_hw_to_dfll(hw);
> +
> + return dfll_enable(td);
> +}
> +
> +static void dfll_clk_disable(struct clk_hw *hw)
> +{
> + struct tegra_dfll *td = clk_hw_to_dfll(hw);
> +
> + dfll_disable(td);
> +}
> +
> +static const struct clk_ops dfll_clk_ops = {
> + .is_enabled = dfll_clk_is_enabled,
> + .enable = dfll_clk_enable,
> + .disable = dfll_clk_disable,
> +};
> +
> +static struct clk_init_data dfll_clk_init_data = {
> + .flags = CLK_IS_ROOT,
> + .ops = &dfll_clk_ops,
> + .num_parents = 0,
> +};
> +
> +/**
> + * dfll_register_clk - register the DFLL output clock with the clock framework
> + * @td: DFLL instance
> + *
> + * Register the DFLL's output clock with the Linux clock framework and register
> + * the DFLL driver as an OF clock provider. Returns 0 upon success or -EINVAL
> + * upon failure.
> + */
Can also return -ENOMEM from of_clk_add_provider.
> +static int dfll_register_clk(struct tegra_dfll *td)
> +{
> + int ret;
> +
> + dfll_clk_init_data.name = td->output_clock_name;
> + td->dfll_clk_hw.init = &dfll_clk_init_data;
> +
> + td->dfll_clk = clk_register(td->dev, &td->dfll_clk_hw);
> + if (IS_ERR(td->dfll_clk)) {
> + dev_err(td->dev, "DFLL clock registration error\n");
> + return -EINVAL;
> + }
> +
> + ret = of_clk_add_provider(td->dev->of_node, of_clk_src_simple_get,
> + td->dfll_clk);
> + if (ret) {
> + dev_err(td->dev, "of_clk_add_provider() failed\n");
> + goto out_unregister_clk;
> + }
> +
> + return 0;
> +
> +out_unregister_clk:
> + clk_unregister(td->dfll_clk);
> +
> + return ret;
> +}
> +
> +/**
> + * dfll_unregister_clk - unregister the DFLL output clock
> + * @td: DFLL instance
> + *
> + * Unregister the DFLL's output clock from the Linux clock framework
> + * and from clkdev. No return value.
> + */
> +static void dfll_unregister_clk(struct tegra_dfll *td)
> +{
> + of_clk_del_provider(td->dev->of_node);
> + clk_unregister(td->dfll_clk);
> + td->dfll_clk = NULL;
> +}
> +
> +/*
> + * Debugfs interface
> + */
> +
> +#ifdef CONFIG_DEBUG_FS
> +
> +static int attr_enable_get(void *data, u64 *val)
> +{
> + struct tegra_dfll *td = data;
> +
> + *val = dfll_is_running(td);
> +
> + return 0;
> +}
> +static int attr_enable_set(void *data, u64 val)
> +{
> + struct tegra_dfll *td = data;
> +
> + return val ? dfll_enable(td) : dfll_disable(td);
> +}
> +DEFINE_SIMPLE_ATTRIBUTE(enable_fops, attr_enable_get, attr_enable_set,
> + "%llu\n");
> +
> +static int attr_rate_get(void *data, u64 *val)
> +{
> + struct tegra_dfll *td = data;
> +
> + *val = dfll_read_monitor_rate(td);
> +
> + return 0;
> +}
> +DEFINE_SIMPLE_ATTRIBUTE(rate_fops, attr_rate_get, NULL, "%llu\n");
> +
> +static int attr_registers_show(struct seq_file *s, void *data)
> +{
> + u32 val, offs;
> + struct tegra_dfll *td = s->private;
> +
> + seq_puts(s, "CONTROL REGISTERS:\n");
> + for (offs = 0; offs <= DFLL_MONITOR_DATA; offs += 4) {
> + if (offs == DFLL_OUTPUT_CFG)
> + val = dfll_i2c_readl(td, offs);
> + else
> + val = dfll_readl(td, offs);
> + seq_printf(s, "[0x%02x] = 0x%08x\n", offs, val);
> + }
> +
> + seq_puts(s, "\nI2C and INTR REGISTERS:\n");
> + for (offs = DFLL_I2C_CFG; offs <= DFLL_I2C_STS; offs += 4)
> + seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
> + dfll_i2c_readl(td, offs));
> + for (offs = DFLL_INTR_STS; offs <= DFLL_INTR_EN; offs += 4)
> + seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
> + dfll_i2c_readl(td, offs));
> +
> + seq_puts(s, "\nINTEGRATED I2C CONTROLLER REGISTERS:\n");
> + offs = DFLL_I2C_CLK_DIVISOR;
> + seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
> + __raw_readl(td->i2c_controller_base + offs));
> +
> + seq_puts(s, "\nLUT:\n");
> + for (offs = 0; offs < 4 * MAX_DFLL_VOLTAGES; offs += 4)
> + seq_printf(s, "[0x%02x] = 0x%08x\n", offs,
> + __raw_readl(td->lut_base + offs));
> +
> + return 0;
> +}
> +
> +static int attr_registers_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, attr_registers_show, inode->i_private);
> +}
> +
> +static const struct file_operations attr_registers_fops = {
> + .open = attr_registers_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +
> +static int dfll_debug_init(struct tegra_dfll *td)
> +{
> + int ret;
> +
> + if (!td || (td->mode == DFLL_UNINITIALIZED))
> + return 0;
> +
> + td->debugfs_dir = debugfs_create_dir("tegra_dfll_fcpu", NULL);
> + if (!td->debugfs_dir)
> + return -ENOMEM;
> +
> + ret = -ENOMEM;
> +
> + if (!debugfs_create_file("enable", S_IRUGO | S_IWUSR,
> + td->debugfs_dir, td, &enable_fops))
> + goto err_out;
> +
> + if (!debugfs_create_file("rate", S_IRUGO,
> + td->debugfs_dir, td, &rate_fops))
> + goto err_out;
> +
> + if (!debugfs_create_file("registers", S_IRUGO,
> + td->debugfs_dir, td, &attr_registers_fops))
> + goto err_out;
> +
> + return 0;
> +
> +err_out:
> + debugfs_remove_recursive(td->debugfs_dir);
> + return ret;
> +}
> +
> +#endif /* CONFIG_DEBUG_FS */
> +
> +/*
> + * DFLL initialization
> + */
> +
> +/**
> + * dfll_set_default_params - program non-output related DFLL parameters
> + * @td: DFLL instance
> + *
> + * During DFLL driver initialization or resume from context loss,
> + * program parameters for the closed loop integrator, DVCO tuning,
> + * voltage droop control and monitor control.
> + */
> +static void dfll_set_default_params(struct tegra_dfll *td)
> +{
> + dfll_tune_low(td);
> + dfll_writel(td, td->droop_ctrl, DFLL_DROOP_CTRL);
> + dfll_writel(td, DFLL_MONITOR_CTRL_FREQ, DFLL_MONITOR_CTRL);
> +}
> +
> +/**
> + * dfll_init_clks - clk_get() the DFLL source clocks
> + * @td: DFLL instance
> + *
> + * Call clk_get() on the DFLL source clocks and save the pointers for later
> + * use. Returns 0 upon success or -ENODEV if one or more of the clocks
> + * couldn't be looked up.
The comment about -ENODEV doesn't seem accurate.
> + */
> +static int dfll_init_clks(struct tegra_dfll *td)
> +{
> + td->ref_clk = devm_clk_get(td->dev, "ref");
> + if (IS_ERR(td->ref_clk)) {
> + dev_err(td->dev, "missing ref clock\n");
> + return PTR_ERR(td->ref_clk);
> + }
> +
> + td->soc_clk = devm_clk_get(td->dev, "soc");
> + if (IS_ERR(td->soc_clk)) {
> + dev_err(td->dev, "missing soc clock\n");
> + return PTR_ERR(td->soc_clk);
> + }
> +
> + td->i2c_clk = devm_clk_get(td->dev, "i2c");
> + if (IS_ERR(td->i2c_clk)) {
> + dev_err(td->dev, "missing i2c clock\n");
> + return PTR_ERR(td->i2c_clk);
> + }
> + td->i2c_clk_rate = clk_get_rate(td->i2c_clk);
The ordering of the various operations which operate on all the clocks
seem to change between each function.
> +
> + return 0;
> +}
> +
> +/**
> + * dfll_init - Prepare the DFLL IP block for use
> + * @td: DFLL instance
> + *
> + * Do everything necessary to prepare the DFLL IP block for use. The
> + * DFLL will be left in DISABLED state. Called by dfll_probe().
> + * Returns 0 upon success, or passes along the error from whatever
> + * function returned it.
> + */
> +static int dfll_init(struct tegra_dfll *td)
> +{
> + int ret;
> +
> + td->ref_rate = clk_get_rate(td->ref_clk);
> + if (td->ref_rate != REF_CLOCK_RATE) {
> + dev_err(td->dev, "unexpected ref clk rate %lu, expecting %lu",
> + td->ref_rate, REF_CLOCK_RATE);
> + return -EINVAL;
> + }
> +
> + if (td->soc->deassert_dvco_reset)
> + td->soc->deassert_dvco_reset();
> +
> + ret = clk_prepare(td->i2c_clk);
> + if (ret) {
> + dev_err(td->dev, "failed to prepare i2c_clk\n");
> + return ret;
> + }
> +
> + ret = clk_prepare(td->ref_clk);
> + if (ret) {
> + dev_err(td->dev, "failed to prepare ref_clk\n");
> + goto di_err1;
> + }
> +
> + ret = clk_prepare(td->soc_clk);
> + if (ret) {
> + dev_err(td->dev, "failed to prepare soc_clk\n");
> + goto di_err2;
> + }
> +
> + pm_runtime_enable(td->dev);
> + pm_runtime_get_sync(td->dev);
> +
> + dfll_set_mode(td, DFLL_DISABLED);
> + dfll_set_default_params(td);
> +
> + if (td->soc->init_clock_trimmers)
> + td->soc->init_clock_trimmers();
> +
> + dfll_set_open_loop_config(td);
> +
> + pm_runtime_put_sync(td->dev);
> +
> + return 0;
> +
> +di_err2:
> + clk_unprepare(td->ref_clk);
> +di_err1:
> + clk_unprepare(td->i2c_clk);
> +
> + if (td->soc->assert_dvco_reset)
> + td->soc->assert_dvco_reset();
> +
> + return ret;
> +}
> +
> +/*
> + * DT data fetch
> + */
> +
> +/**
> + * read_dt_param - helper function for reading required parameters from the DT
> + * @td: DFLL instance
> + * @param: DT property name
> + * @dest: output pointer for the value read
> + *
> + * Read a required numeric parameter from the DFLL device node, or complain
> + * if the property doesn't exist. Returns a boolean indicating success for
> + * easy chaining of multiple calls to this function.
> + */
> +static bool read_dt_param(struct tegra_dfll *td, const char *param, u32 *dest)
> +{
> + int err = of_property_read_u32(td->dev->of_node, param, dest);
> +
> + if (err < 0) {
> + dev_err(td->dev, "failed to read DT parameter %s: %d\n",
> + param, err);
> + return false;
> + }
> +
> + return true;
> +}
> +
> +/**
> + * dfll_fetch_common_params - read DFLL parameters from the device tree
> + * @td: DFLL instance
> + *
> + * Read all the DT parameters that are common to both I2C and PWM operation.
> + * Returns 0 on success or -EINVAL on any failure.
> + */
> +static int dfll_fetch_common_params(struct tegra_dfll *td)
> +{
> + bool ok = true;
> +
> + ok &= read_dt_param(td, "nvidia,droop-ctrl", &td->droop_ctrl);
> +
> + if (of_property_read_string(td->dev->of_node, "clock-output-names",
> + &td->output_clock_name)) {
> + dev_err(td->dev, "missing clock-output-names property\n");
> + ok = false;
> + }
> +
> + return ok ? 0 : -EINVAL;
> +}
> +
> +/*
> + * API exported to per-SoC platform drivers
> + */
> +
> +/**
> + * tegra_dfll_register - probe a Tegra DFLL device
> + * @pdev: DFLL platform_device *
> + * @soc: Per-SoC integration and characterization data for this DFLL instance
> + *
> + * Probe and initialize a DFLL device instance. Intended to be called
> + * by a SoC-specific shim driver that passes in per-SoC integration
> + * and configuration data via @soc. Returns 0 on success or -err on failure.
> + */
> +int tegra_dfll_register(struct platform_device *pdev,
> + struct tegra_dfll_soc_data *soc)
> +{
> + struct resource *mem;
> + struct tegra_dfll *td;
> + int ret;
> +
> + td = devm_kzalloc(&pdev->dev, sizeof(*td), GFP_KERNEL);
> + if (!td)
> + return -ENOMEM;
> + td->dev = &pdev->dev;
> + platform_set_drvdata(pdev, td);
> +
> + if (!soc) {
> + dev_err(td->dev, "no tegra_dfll_soc_data provided\n");
> + return -EINVAL;
> + }
Could check this parameter first to avoid a potentially unnecessary allocation.
> + td->soc = soc;
> +
> + td->vdd_reg = devm_regulator_get(td->dev, "vdd-cpu");
> + if (IS_ERR(td->vdd_reg)) {
> + dev_err(td->dev, "couldn't get vdd_cpu regulator\n");
> + return PTR_ERR(td->vdd_reg);
> + }
> +
> + ret = dfll_fetch_common_params(td);
> + if (ret) {
> + dev_err(td->dev, "couldn't parse device tree parameters\n");
> + return ret;
> + }
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!mem) {
> + dev_err(td->dev, "no control register resource\n");
> + return -ENODEV;
> + }
> +
> + td->base = devm_ioremap(td->dev, mem->start, resource_size(mem));
> + if (!td->base) {
> + dev_err(td->dev, "couldn't ioremap DFLL control registers\n");
> + return -ENODEV;
> + }
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + if (!mem) {
> + dev_err(td->dev, "no i2c_base resource\n");
> + return -ENODEV;
> + }
> +
> + td->i2c_base = devm_ioremap(td->dev, mem->start, resource_size(mem));
> + if (!td->i2c_base) {
> + dev_err(td->dev, "couldn't ioremap i2c_base resource\n");
> + return -ENODEV;
> + }
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 2);
> + if (!mem) {
> + dev_err(td->dev, "no i2c_controller_base resource\n");
> + return -ENODEV;
> + }
> +
> + td->i2c_controller_base = devm_ioremap(td->dev, mem->start,
> + resource_size(mem));
> + if (!td->i2c_controller_base) {
> + dev_err(td->dev,
> + "couldn't ioremap i2c_controller_base resource\n");
> + return -ENODEV;
> + }
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 3);
> + if (!mem) {
> + dev_err(td->dev, "no lut_base resource\n");
> + return -ENODEV;
> + }
> +
> + td->lut_base = devm_ioremap(td->dev, mem->start, resource_size(mem));
> + if (!td->lut_base) {
> + dev_err(td->dev,
> + "couldn't ioremap lut_base resource\n");
> + return -ENODEV;
> + }
> +
> + ret = dfll_init_clks(td);
> + if (ret) {
> + dev_err(&pdev->dev, "DFLL clock init error\n");
> + return ret;
> + }
> +
> + /* Enable the clocks and set the device up */
> + ret = dfll_init(td);
> + if (ret)
> + return ret;
> +
> + ret = dfll_register_clk(td);
> + if (ret) {
> + dev_err(&pdev->dev, "DFLL clk registration failed\n");
> + return ret;
> + }
> +
> +#ifdef CONFIG_DEBUG_FS
> + dfll_debug_init(td);
> +#endif
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(tegra_dfll_register);
> +
> +/**
> + * tegra_dfll_unregister - release all of the DFLL driver resources for a device
> + * @pdev: DFLL platform_device *
> + *
> + * Unbind this driver from the DFLL hardware device represented by
> + * @pdev. The DFLL must be disabled for this to succeed. Returns 0
> + * upon success or -EBUSY if the DFLL is still active.
> + */
> +int tegra_dfll_unregister(struct platform_device *pdev)
> +{
> + struct tegra_dfll *td = platform_get_drvdata(pdev);
> +
> + /* Try to prevent removal while the DFLL is active */
> + if (td->mode != DFLL_DISABLED) {
> + dev_err(&pdev->dev,
> + "must disable DFLL before removing driver\n");
> + return -EBUSY;
> + }
> +
> + debugfs_remove_recursive(td->debugfs_dir);
> +
> + dfll_unregister_clk(td);
> + pm_runtime_disable(&pdev->dev);
> +
> + clk_unprepare(td->soc_clk);
> + clk_unprepare(td->ref_clk);
> + clk_unprepare(td->i2c_clk);
> +
> + if (td->soc->assert_dvco_reset)
> + td->soc->assert_dvco_reset();
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(tegra_dfll_unregister);
> diff --git a/drivers/clk/tegra/clk-dfll.h b/drivers/clk/tegra/clk-dfll.h
> new file mode 100644
> index 0000000..fbf90c4
> --- /dev/null
> +++ b/drivers/clk/tegra/clk-dfll.h
> @@ -0,0 +1,55 @@
> +/*
> + * clk-dfll.h - prototypes and macros for the Tegra DFLL clocksource driver
> + * Copyright (C) 2013 NVIDIA Corporation. All rights reserved.
> + *
> + * Aleksandr Frid <afrid at nvidia.com>
> + * Paul Walmsley <pwalmsley at nvidia.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#ifndef __DRIVERS_CLK_TEGRA_CLK_DFLL_H
> +#define __DRIVERS_CLK_TEGRA_CLK_DFLL_H
> +
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +
> +/**
> + * struct tegra_dfll_soc - SoC-specific hooks/integration for the DFLL driver
Should be tegra_dfll_soc_data.
> + * @opp_dev: struct device * that holds the OPP table for the DFLL
> + * @min_millivolts: minimum voltage (in mV) that the DFLL can operate
> + * @tune0_low: DFLL tuning register 0 (low voltage range)
> + * @tune0_high: DFLL tuning register 0 (high voltage range)
> + * @tune1: DFLL tuning register 1
> + * @assert_dvco_reset: fn ptr to place the DVCO in reset
> + * @deassert_dvco_reset: fn ptr to release the DVCO reset
> + * @set_clock_trimmers_high: fn ptr to tune clock trimmers for high voltage
> + * @set_clock_trimmers_low: fn ptr to tune clock trimmers for low voltage
> + */
> +struct tegra_dfll_soc_data {
> + struct device *opp_dev;
> + unsigned int min_millivolts;
> + u32 tune0_low;
> + u32 tune0_high;
> + u32 tune1;
> + void (*assert_dvco_reset)(void);
> + void (*deassert_dvco_reset)(void);
> + void (*init_clock_trimmers)(void);
> + void (*set_clock_trimmers_high)(void);
> + void (*set_clock_trimmers_low)(void);
> +};
> +
> +int tegra_dfll_register(struct platform_device *pdev,
> + struct tegra_dfll_soc_data *soc);
> +int tegra_dfll_unregister(struct platform_device *pdev);
> +int tegra_dfll_runtime_suspend(struct device *dev);
> +int tegra_dfll_runtime_resume(struct device *dev);
> +
> +#endif /* __DRIVERS_CLK_TEGRA_CLK_DFLL_H */
> --
> 1.8.1.5
>
> --
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