[PATCH 2/2] cpufreq: add cpufreq driver for Mediatek MT8173 SoC
Yingjoe Chen
yingjoe.chen at mediatek.com
Tue Jan 13 23:43:39 PST 2015
Hi,
On Fri, 2015-01-09 at 17:54 +0800, pi-cheng.chen wrote:
> When doing DVFS on MT8173 SoC, 2 rules should be followed to make sure the
> SoC works properly:
> 1. When doing frequency scaling of CPUs, the clock source should be switched
> to another PLL, then switched back to the orignal until it's stable.
> 2. When doing voltage scaling of CA57 cluster, Vproc and Vsram need to be
> controlled concurrently and 2 limitations should be followed:
> a. Vsram > Vproc
> b. Vsram - Vproc < 200 mV
It seems to me this is not much different then other mtk big little
SoCs. Is it possible to aim to support both mt8173 & mt8135 with this
driver?
> To address these needs, we reuse cpufreq-dt but do voltage scaling in the
> cpufreq notifier.
>
> Signed-off-by: pi-cheng.chen <pi-cheng.chen at linaro.org>
> ---
> drivers/cpufreq/Kconfig.arm | 6 +
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/mt8173-cpufreq.c | 459 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 466 insertions(+)
> create mode 100644 drivers/cpufreq/mt8173-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 0f9a2c3..97ed7dd 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -255,3 +255,9 @@ config ARM_PXA2xx_CPUFREQ
> This add the CPUFreq driver support for Intel PXA2xx SOCs.
>
> If in doubt, say N.
> +
> +config ARM_MT8173_CPUFREQ
> + bool "Mediatek MT8173 CPUFreq support"
> + depends on ARCH_MEDIATEK && CPUFREQ_DT && REGULATOR
> + help
> + This adds the CPUFreq driver support for Mediatek MT8173 SoC.
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index b3ca7b0..67b7f17 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_ARM_SA1110_CPUFREQ) += sa1110-cpufreq.o
> obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o
> obj-$(CONFIG_ARM_TEGRA_CPUFREQ) += tegra-cpufreq.o
> obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ) += vexpress-spc-cpufreq.o
> +obj-$(CONFIG_ARM_MT8173_CPUFREQ) += mt8173-cpufreq.o
>
> ##################################################################################
> # PowerPC platform drivers
> diff --git a/drivers/cpufreq/mt8173-cpufreq.c b/drivers/cpufreq/mt8173-cpufreq.c
> new file mode 100644
> index 0000000..b578c10
> --- /dev/null
> +++ b/drivers/cpufreq/mt8173-cpufreq.c
> @@ -0,0 +1,459 @@
> +/*
> +* Copyright (c) 2015 Linaro.
> +* Author: Pi-Cheng Chen <pi-cheng.chen at linaro.org>
> +*
> +* 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.
> +*/
> +
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/cpufreq.h>
> +#include <linux/cpufreq-dt.h>
> +#include <linux/cpumask.h>
> +#include <linux/slab.h>
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/cpu.h>
> +#include <linux/pm_opp.h>
> +
> +#define CPUCLK_MUX_ARMPLL 0x1
> +#define CPUCLK_MUX_MAINPLL 0x2
> +#define VOLT_SHIFT_LIMIT 150000
> +
> +enum {
> + LITTLE_CLUSTER = 0,
> + BIG_CLUSTER,
> + NR_CLUSTERS
> +};
> +
> +static struct cluster_dvfs_info {
> + int cpu;
> + struct cpumask cpus;
> + struct device *cpu_dev;
> + struct regulator *proc_reg;
> + struct regulator *sram_reg;
> + int inter_volt;
> + u32 volt_tol;
> +} *dvfs_info;
> +
> +static unsigned long mainpll_freq;
> +static void __iomem *clk_mux_regs;
> +static spinlock_t lock;
> +
> +static void cpuclk_mux_set(int cluster, u32 sel)
> +{
> + u32 val;
> + u32 mask = 0x3;
> +
> + if (cluster == BIG_CLUSTER) {
> + mask <<= 2;
> + sel <<= 2;
> + }
> +
> + spin_lock(&lock);
> +
> + val = readl(clk_mux_regs);
> + val = (val & ~mask) | sel;
> + writel(val, clk_mux_regs);
> +
> + spin_unlock(&lock);
> +}
> +
> +static int mt8173_cpufreq_voltage_step(struct cluster_dvfs_info *dvfs,
> + unsigned long old_vproc,
> + unsigned long new_vproc)
> +{
> + int cur_vsram, cur_vproc, target_volt, tol;
> +
> + if (old_vproc > new_vproc) {
> + while (1) {
> + cur_vsram = regulator_get_voltage(dvfs->sram_reg);
> + if (cur_vsram - new_vproc < VOLT_SHIFT_LIMIT &&
> + cur_vsram > new_vproc) {
> + tol = new_vproc * dvfs->volt_tol / 100;
> + regulator_set_voltage_tol(dvfs->proc_reg,
> + new_vproc, tol);
> + break;
> + }
> +
> + target_volt = cur_vsram - VOLT_SHIFT_LIMIT;
> + tol = target_volt * dvfs->volt_tol / 100;
I don't quite get the logic for tol calculation here. What's the
expected value for volt_tol? Care to explain?
> + regulator_set_voltage_tol(dvfs->proc_reg, target_volt,
> + tol);
> +
> + cur_vproc = regulator_get_voltage(dvfs->proc_reg);
> + target_volt = cur_vproc + 1;
> + tol = target_volt * dvfs->volt_tol / 100;
> + regulator_set_voltage_tol(dvfs->sram_reg, target_volt,
> + tol);
> + }
> + } else if (old_vproc < new_vproc) {
> + while (1) {
> + cur_vsram = regulator_get_voltage(dvfs->sram_reg);
> + if (cur_vsram - new_vproc < VOLT_SHIFT_LIMIT &&
> + cur_vsram > new_vproc) {
> + tol = new_vproc * dvfs->volt_tol / 100;
> + regulator_set_voltage_tol(dvfs->proc_reg,
> + new_vproc, tol);
> + break;
> + }
> +
> + cur_vproc = regulator_get_voltage(dvfs->proc_reg);
> + target_volt = cur_vproc + VOLT_SHIFT_LIMIT;
> + tol = target_volt * dvfs->volt_tol / 100;
> + regulator_set_voltage_tol(dvfs->sram_reg, target_volt,
> + tol);
> +
> + if (new_vproc - cur_vproc > VOLT_SHIFT_LIMIT) {
> + cur_vsram = regulator_get_voltage(
> + dvfs->sram_reg);
> + target_volt = cur_vsram - 1;
> + tol = target_volt * dvfs->volt_tol / 100;
> + regulator_set_voltage_tol(dvfs->proc_reg,
> + target_volt, tol);
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int get_opp_voltage(struct device *dev, unsigned long freq_hz)
> +{
> + struct dev_pm_opp *opp;
> + int volt;
> +
> + rcu_read_lock();
> + opp = dev_pm_opp_find_freq_ceil(dev, &freq_hz);
> + if (IS_ERR(opp)) {
> + rcu_read_unlock();
> + pr_err("%s: failed to find OPP for %lu\n", __func__, freq_hz);
> + return PTR_ERR(opp);
> + }
> + volt = dev_pm_opp_get_voltage(opp);
> + rcu_read_unlock();
> +
> + return volt;
> +}
> +
> +static int mt8173_cpufreq_get_intermediate_voltage(int cluster)
> +{
> + struct cluster_dvfs_info *dvfs = &dvfs_info[cluster];
> +
> + if (dvfs->inter_volt == 0)
> + dvfs->inter_volt = get_opp_voltage(dvfs->cpu_dev,
> + mainpll_freq);
> +
> + return dvfs->inter_volt;
> +}
> +
> +static void mt8173_cpufreq_set_voltage(int cluster, int old_volt, int new_volt)
> +{
> + struct cluster_dvfs_info *dvfs = &dvfs_info[cluster];
> + int ret = 0;
> +
> + if (cluster == LITTLE_CLUSTER) {
> + int tol;
> +
> + tol = new_volt * dvfs->volt_tol / 100;
> + ret = regulator_set_voltage_tol(dvfs->proc_reg, new_volt, tol);
> + } else {
> + ret = mt8173_cpufreq_voltage_step(dvfs, old_volt, new_volt);
> + }
> +
> + if (ret)
> + pr_err("%s: cluster%d failed to scale voltage (%dmV to %dmV)",
> + __func__, cluster, old_volt, new_volt);
> +}
It seems the only reason to check if it is a BIG or LITTLE cluster is to
control vsram correctly. If we assume we need to do the control whenever
sram_reg exists, we can drop all the BIG/LITTLE cluster check. I think
this will make code looks more compact and generic.
> +
> +static int mt8173_cpufreq_notify(struct notifier_block *nb,
> + unsigned long action, void *data)
> +{
> + struct cpufreq_freqs *freqs = data;
> + struct cluster_dvfs_info *dvfs;
> + unsigned long old_volt, new_volt, inter_volt;
> + int cluster;
> +
> + if (freqs->cpu == dvfs_info[BIG_CLUSTER].cpu)
> + cluster = BIG_CLUSTER;
> + else if (freqs->cpu == dvfs_info[LITTLE_CLUSTER].cpu)
> + cluster = LITTLE_CLUSTER;
> + else
> + return NOTIFY_DONE;
> +
> + dvfs = &dvfs_info[cluster];
> +
> + old_volt = regulator_get_voltage(dvfs->proc_reg);
> +
> + new_volt = get_opp_voltage(dvfs->cpu_dev, freqs->new * 1000);
> + inter_volt = mt8173_cpufreq_get_intermediate_voltage(cluster);
This is only used in PRECHANGE, please move this inside the if.
> +
> + if (action == CPUFREQ_PRECHANGE) {
> + if (old_volt < inter_volt || old_volt < new_volt) {
> + new_volt = inter_volt > new_volt ?
> + inter_volt : new_volt;
> + mt8173_cpufreq_set_voltage(cluster, old_volt,
> + new_volt);
> + }
> +
> + cpuclk_mux_set(cluster, CPUCLK_MUX_MAINPLL);
> + } else if (action == CPUFREQ_POSTCHANGE) {
> + cpuclk_mux_set(cluster, CPUCLK_MUX_ARMPLL);
> +
> + if (new_volt < old_volt)
> + mt8173_cpufreq_set_voltage(cluster, old_volt,
> + new_volt);
> + }
> +
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block mt8173_cpufreq_nb = {
> + .notifier_call = mt8173_cpufreq_notify,
> +};
> +
> +static struct cpufreq_dt_platform_data *pd;
Please drop this global variable. You can return it from
cpufreq_dt_pdata_init and pass to all the function need it.
> +
> +static int cpu_in_domain_list(struct list_head *domain_list, int cpu)
> +{
> + struct list_head *node;
> +
> + list_for_each(node, domain_list) {
> + struct cpufreq_cpu_domain *domain;
> +
> + domain = container_of(node, struct cpufreq_cpu_domain, node);
> + if (cpumask_test_cpu(cpu, &domain->cpus))
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> +static void cpufreq_dt_pdata_release(void)
> +{
> + if (!pd)
> + return;
> +
> + if (!list_empty(&pd->domain_list)) {
> + struct list_head *node, *tmp;
> + struct cpufreq_cpu_domain *domain;
> +
> + list_for_each_safe(node, tmp, &pd->domain_list) {
> + list_del(node);
> + domain = container_of(node, struct cpufreq_cpu_domain,
> + node);
> + kfree(domain);
> + }
> + }
> +
> + kfree(pd);
> +}
> +
> +static int cpufreq_dt_pdata_init(void)
> +{
> + int cpu;
> +
> + pd = kmalloc(sizeof(*pd), GFP_KERNEL);
> + if (!pd)
> + return -ENOMEM;
> +
> + pd->independent_clocks = 1,
> + INIT_LIST_HEAD(&pd->domain_list);
> +
> + for_each_possible_cpu(cpu) {
> + struct cpufreq_cpu_domain *new_domain;
> +
> + if (cpu_in_domain_list(&pd->domain_list, cpu))
> + continue;
> +
> + new_domain = kzalloc(sizeof(*new_domain), GFP_KERNEL);
> + if (!new_domain) {
> + cpufreq_dt_pdata_release();
> + return -ENOMEM;
> + }
> +
> + cpumask_copy(&new_domain->cpus,
> + &cpu_topology[cpu].core_sibling);
> + list_add(&new_domain->node, &pd->domain_list);
> + }
> +
> + return 0;
> +}
> +
> +static void mt8173_cpufreq_dvfs_info_release(void)
> +{
> + int i;
> +
> + if (!dvfs_info)
> + return;
> +
> + for (i = 0; i < NR_CLUSTERS; ++i) {
> + struct cluster_dvfs_info *dvfs = &dvfs_info[i];
> +
> + if (!IS_ERR_OR_NULL(dvfs->proc_reg))
> + regulator_put(dvfs->proc_reg);
> +
> + if (!IS_ERR_OR_NULL(dvfs->sram_reg))
> + regulator_put(dvfs->sram_reg);
> + }
> +
> + if (clk_mux_regs)
> + iounmap(clk_mux_regs);
> +}
> +
> +static int mt8173_cpufreq_dvfs_info_init(void)
> +{
> + struct list_head *node;
> + struct device_node *np;
> + struct clk *mainpll;
> + int i, ret;
> +
> + dvfs_info = kzalloc(sizeof(*dvfs) * NR_CLUSTERS, GFP_KERNEL);
> + if (!dvfs_info)
> + return -ENOMEM;
> +
> + list_for_each(node, &pd->domain_list) {
> + struct cpufreq_cpu_domain *domain = container_of(
> + node, struct cpufreq_cpu_domain, node);
> + int cpu = cpumask_next(0, &domain->cpus);
> +
> + np = of_get_cpu_node(cpu, NULL);
> +
> + if (of_property_match_string(np, "compatible",
> + "arm,cortex-a53") >= 0)
> + cpumask_copy(&dvfs_info[LITTLE_CLUSTER].cpus,
> + &domain->cpus);
> + else if (of_property_match_string(np, "compatible",
> + "arm,cortex-a57") >= 0)
> + cpumask_copy(&dvfs_info[BIG_CLUSTER].cpus,
> + &domain->cpus);
> + else {
> + of_node_put(np);
> + pr_err("%s: unknown CPU core\n", __func__);
> + return -EINVAL;
> + }
> +
> + of_node_put(np);
> + }
It seems you hardcode the match CPU here to know which is big/little
cluster. If we still need this information, should we add this to
topology, maybe something similar to capacity in arm topology, instead
of coding here?
> +
> + for (i = 0; i < NR_CLUSTERS; i++) {
> + struct cluster_dvfs_info *dvfs = &dvfs_info[i];
> + int cpu;
> +
> + for_each_cpu_mask(cpu, dvfs->cpus) {
> + struct device_node *np;
> +
> + dvfs->cpu_dev = get_cpu_device(cpu);
> + dvfs->proc_reg = regulator_get(dvfs->cpu_dev, "proc");
> + if (IS_ERR(dvfs->proc_reg))
> + continue;
> +
> + dvfs->cpu = cpu;
> + dvfs->sram_reg = regulator_get(dvfs->cpu_dev, "sram");
> +
> + np = of_node_get(dvfs->cpu_dev->of_node);
> + of_property_read_u32(np, "voltage-tolerance",
> + &dvfs->volt_tol);
> + of_node_put(np);
> + break;
> + }
> +
> + if (IS_ERR(dvfs->proc_reg)) {
> + pr_err("%s: no proc regulator for cluster %d\n",
> + __func__, i);
> + ret = -ENODEV;
> + goto dvfs_info_release;
> + }
> +
> + if (IS_ERR(dvfs->sram_reg) && BIG_CLUSTER == i) {
> + pr_err("%s: no sram regulator for cluster %d\n",
> + __func__, i);
> + ret = -ENODEV;
> + goto dvfs_info_release;
> + }
> + }
> +
> + mainpll = __clk_lookup("mainpll");
> + if (!mainpll) {
> + pr_err("failed to get mainpll clk\n");
> + ret = -ENOENT;
> + goto dvfs_info_release;
> + }
> + mainpll_freq = clk_get_rate(mainpll);
> +
> + np = of_find_compatible_node(NULL, NULL, "mediatek,mt8173-infrasys");
> + if (!np) {
> + pr_err("failed to find clock mux registers\n");
> + ret = -ENODEV;
> + goto dvfs_info_release;
> + }
> +
> + clk_mux_regs = of_iomap(np, 0);
> + if (!clk_mux_regs) {
> + pr_err("failed to map clock mux registers\n");
> + ret = -EFAULT;
> + goto dvfs_info_release;
> + }
> + of_node_put(np);
This is already used by mt8173 clock driver, and you are directly
accessing it registers to control clock mux. I think you should add
these 2 clk to clock driver and use clk API to control it. Also you can
drop the lock init below if you do this.
Joe.C
> +
> + spin_lock_init(&lock);
> +
> + return 0;
> +
> +dvfs_info_release:
> + mt8173_cpufreq_dvfs_info_release();
> + return ret;
> +}
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