[PATCH v4 1/3] pwm: driver for qualcomm ipq6018 pwm block
Uwe Kleine-König
u.kleine-koenig at pengutronix.de
Mon Jul 5 00:20:55 PDT 2021
Hello Baruch,
On Sun, Jun 27, 2021 at 08:24:04AM +0300, Baruch Siach wrote:
> Driver for the PWM block in Qualcomm IPQ6018 line of SoCs. Based on
> driver from downstream Codeaurora kernel tree. Removed support for older
> (V1) variants because I have no access to that hardware.
>
> Tested on IPQ6010 based hardware.
>
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
> v4:
>
> Use div64_u64() to fix link for 32-bit targets ((kernel test robot
> <lkp at intel.com>, Uwe Kleine-König)
>
> v3:
>
> s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)
>
> Fix integer overflow on 32-bit targets (kernel test robot <lkp at intel.com>)
>
> v2:
>
> Address Uwe Kleine-König review comments:
>
> Fix period calculation when out of range
>
> Don't set period larger than requested
>
> Remove PWM disable on configuration change
>
> Implement .apply instead of non-atomic .config/.enable/.disable
>
> Don't modify PWM on .request/.free
>
> Check pwm_div underflow
>
> Fix various code and comment formatting issues
>
> Other changes:
>
> Use u64 divisor safe division
>
> Remove now empty .request/.free
> ---
> drivers/pwm/Kconfig | 12 +++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-ipq.c | 238 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 251 insertions(+)
> create mode 100644 drivers/pwm/pwm-ipq.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index c76adedd58c9..08add845596f 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -260,6 +260,18 @@ config PWM_INTEL_LGM
> To compile this driver as a module, choose M here: the module
> will be called pwm-intel-lgm.
>
> +config PWM_IPQ
> + tristate "IPQ PWM support"
> + depends on ARCH_QCOM || COMPILE_TEST
> + depends on HAVE_CLK && HAS_IOMEM
> + help
> + Generic PWM framework driver for IPQ PWM block which supports
> + 4 pwm channels. Each of the these channels can be configured
> + independent of each other.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called pwm-ipq.
> +
> config PWM_IQS620A
> tristate "Azoteq IQS620A PWM support"
> depends on MFD_IQS62X || COMPILE_TEST
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 708840b7fba8..7402feae4b36 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -22,6 +22,7 @@ obj-$(CONFIG_PWM_IMX1) += pwm-imx1.o
> obj-$(CONFIG_PWM_IMX27) += pwm-imx27.o
> obj-$(CONFIG_PWM_IMX_TPM) += pwm-imx-tpm.o
> obj-$(CONFIG_PWM_INTEL_LGM) += pwm-intel-lgm.o
> +obj-$(CONFIG_PWM_IPQ) += pwm-ipq.o
> obj-$(CONFIG_PWM_IQS620A) += pwm-iqs620a.o
> obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o
> obj-$(CONFIG_PWM_KEEMBAY) += pwm-keembay.o
> diff --git a/drivers/pwm/pwm-ipq.c b/drivers/pwm/pwm-ipq.c
> new file mode 100644
> index 000000000000..966b051573c8
> --- /dev/null
> +++ b/drivers/pwm/pwm-ipq.c
> @@ -0,0 +1,238 @@
> +// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
> +/*
> + * Copyright (c) 2016-2017, 2020 The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/math64.h>
> +#include <linux/of_device.h>
> +
> +#define CLK_SRC_FREQ (100*1000*1000)
> +#define MAX_PWM_DEVICES 4
MAX_PWM_DEVICES is only used once, in my book this doesn't need a define
then. (But if you still want to keep it, that's fine for me, too.)
> +/*
> + * Enable bit is set to enable output toggling in pwm device.
> + * Update bit is set to reflect the changed divider and high duration
> + * values in register.
> + */
> +#define PWM_ENABLE 0x80000000
> +#define PWM_UPDATE 0x40000000
> +
> +/* The frequency range supported is 1Hz to 100MHz */
> +#define MIN_PERIOD_NS 10
> +#define MAX_PERIOD_NS 1000000000
Please use a driver prefix for these defines.
> +
> +/*
> + * The max value specified for each field is based on the number of bits
> + * in the pwm control register for that field
> + */
> +#define MAX_PWM_CFG 0xFFFF
> +
> +#define PWM_CTRL_HI_SHIFT 16
> +
> +#define PWM_CFG_REG0 0 /*PWM_DIV PWM_HI*/
> +#define PWM_CFG_REG1 1 /*ENABLE UPDATE PWM_PRE_DIV*/
> +
> +struct ipq_pwm_chip {
> + struct pwm_chip chip;
> + struct clk *clk;
> + void __iomem *mem;
> +};
> +
> +static struct ipq_pwm_chip *to_ipq_pwm_chip(struct pwm_chip *chip)
> +{
> + return container_of(chip, struct ipq_pwm_chip, chip);
> +}
> +
> +static unsigned ipq_pwm_reg_offset(struct pwm_device *pwm, unsigned reg)
> +{
> + return ((pwm->hwpwm * 2) + reg) * 4;
> +}
> +
> +static void config_div_and_duty(struct pwm_device *pwm, int pre_div,
> + unsigned long long pwm_div, unsigned long period_ns,
> + unsigned long long duty_ns)
Please also use a consistent prefix for function names.
I suggest to use u64 for some of the parameters. While this doesn't
change anything, it is cleaner as the caller passes variables of this
type.
> +{
> + unsigned long hi_dur;
> + unsigned long long quotient;
> + unsigned long val = 0;
> + struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> +
> + /*
> + * high duration = pwm duty * (pwm div + 1)
> + * pwm duty = duty_ns / period_ns
> + */
> + quotient = (pwm_div + 1) * duty_ns;
> + hi_dur = div64_u64(quotient, period_ns);
> +
> + val |= ((hi_dur & MAX_PWM_CFG) << PWM_CTRL_HI_SHIFT);
> + val |= (pwm_div & MAX_PWM_CFG);
> + writel(val, ipq_chip->mem + ipq_pwm_reg_offset(pwm, PWM_CFG_REG0));
I consider it a bit irritating that the mask is called ...CFG but the
shift define is called ..._CTRL_....
I suggest something like:
#define IPQ_PWM_REG0 ...
#define IPQ_PWM_REG0_HI 0xffff0000
#define IPQ_PWM_REG0_DIV 0x0000ffff
...
val = FIELD_PREP(IPQ_PWM_REG0_HI, hi_dur) |
FIELD_PREP(IPQ_PWM_REG0_DIV, pwm_div);
ipq_pwm_writel(ipq_chip, val, PWM_CFG_REG0);
> + val = pre_div & MAX_PWM_CFG;
> + writel(val, ipq_chip->mem + ipq_pwm_reg_offset(pwm, PWM_CFG_REG1));
> +}
> +
> +static int ipq_pwm_enable(struct pwm_device *pwm)
This is only called once. The caller (ipq_pwm_apply()) just before
called config_div_and_duty() which already wrote PWM_CFG_REG1. If you
unroll these calls you might fix a glitch or make it more unlikely.
> +{
> + struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> + unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
> + unsigned long val;
> +
> + val = readl(ipq_chip->mem + offset);
> + val |= PWM_ENABLE | PWM_UPDATE;
> + writel(val, ipq_chip->mem + offset);
> +
> + return 0;
> +}
> +
> +static void ipq_pwm_disable(struct pwm_device *pwm)
> +{
> + struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> + unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
> + unsigned long val;
> +
> + val = readl(ipq_chip->mem + offset);
> + val |= PWM_UPDATE;
> + val &= ~PWM_ENABLE;
> + writel(val, ipq_chip->mem + offset);
> +}
> +
> +static int ipq_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(chip);
> + unsigned long freq;
> + int pre_div, close_pre_div, close_pwm_div;
> + int pwm_div;
> + long long diff;
> + unsigned long rate = clk_get_rate(ipq_chip->clk);
> + unsigned long min_diff = rate;
> + uint64_t fin_ps;
> + u64 period_ns, duty_ns;
> +
> + if (state->period < MIN_PERIOD_NS)
> + return -ERANGE;
MIN_PERIOD_NS depends on clk_get_rate(ipq_chip->clk), doesn't it?
> + period_ns = min_t(u64, state->period, MAX_PERIOD_NS);
> + duty_ns = min_t(u64, state->duty_cycle, period_ns);
If you define MAX_PERIOD_NS as (u64)1000000000 you can just use min().
> +
> + /* freq in Hz for period in nano second*/
Space before the closing */ please
> + freq = div64_u64(NSEC_PER_SEC, period_ns);
> + fin_ps = div64_u64(NSEC_PER_SEC * 1000ULL, rate);
> + close_pre_div = MAX_PWM_CFG;
> + close_pwm_div = MAX_PWM_CFG;
> +
> + for (pre_div = 0; pre_div <= MAX_PWM_CFG; pre_div++) {
> + pwm_div = DIV64_U64_ROUND_CLOSEST(period_ns * 1000,
> + fin_ps * (pre_div + 1));
> + pwm_div--;
> + if (pwm_div < 0 || pwm_div > MAX_PWM_CFG)
> + continue;
> +
> + diff = ((uint64_t)freq * (pre_div + 1) * (pwm_div + 1))
> + - (uint64_t)rate;
> +
> + if (diff < 0) /* period larger than requested */
> + continue;
> + if (diff == 0) { /* bingo */
> + close_pre_div = pre_div;
> + close_pwm_div = pwm_div;
> + break;
> + }
> + if (diff < min_diff) {
> + min_diff = diff;
> + close_pre_div = pre_div;
> + close_pwm_div = pwm_div;
> + }
I didn't check deeply, but I assume this calculation can be done more
efficiently. Also I wonder if DIV64_U64_ROUND_CLOSEST is right. When you
implement a .get_state() callback (which usually helps me to understand
how the hardware works) I'm willing to take a closer look.
> + }
> +
> + /* config divider values for the closest possible frequency */
> + config_div_and_duty(pwm, close_pre_div, close_pwm_div,
> + period_ns, duty_ns);
> + if (state->enabled)
> + ipq_pwm_enable(pwm);
> + else
> + ipq_pwm_disable(pwm);
> +
> + return 0;
> +}
> +
> +static struct pwm_ops ipq_pwm_ops = {
> + .apply = ipq_pwm_apply,
Please implement a .get_state() function. (And in general, test your patch
with PWM_DEBUG enabled.)
> + .owner = THIS_MODULE,
> +};
> +
> +static int ipq_pwm_probe(struct platform_device *pdev)
> +{
> + struct ipq_pwm_chip *pwm;
> + struct device *dev;
> + int ret;
> +
> + dev = &pdev->dev;
This can go to the line declaring dev.
> + pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL);
> + if (!pwm)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, pwm);
> +
> + pwm->mem = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(pwm->mem))
> + return PTR_ERR(pwm->mem);
> +
> + pwm->clk = devm_clk_get(dev, "core");
> + if (IS_ERR(pwm->clk))
Error message please. Preferably using dev_err_probe().
> + return PTR_ERR(pwm->clk);
> +
> + ret = clk_set_rate(pwm->clk, CLK_SRC_FREQ);
> + if (ret)
ditto.
> + return ret;
empty line here?
> + ret = clk_prepare_enable(pwm->clk);
> + if (ret)
ditto.
> + return ret;
> +
> + pwm->chip.dev = dev;
> + pwm->chip.ops = &ipq_pwm_ops;
> + pwm->chip.npwm = MAX_PWM_DEVICES;
> +
> + ret = pwmchip_add(&pwm->chip);
> + if (ret < 0) {
> + dev_err_probe(dev, ret, "pwmchip_add() failed\n");
> + clk_disable_unprepare(pwm->clk);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int ipq_pwm_remove(struct platform_device *pdev)
> +{
> + struct ipq_pwm_chip *pwm = platform_get_drvdata(pdev);
> +
> + pwmchip_remove(&pwm->chip);
clk_disable_unprepare missing here.
> +
> + return 0;
> +}
> +
> +static const struct of_device_id pwm_ipq_dt_match[] = {
> + { .compatible = "qcom,ipq6018-pwm", },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, pwm_ipq_dt_match);
> +
> +static struct platform_driver ipq_pwm_driver = {
> + .driver = {
> + .name = "ipq-pwm",
> + .owner = THIS_MODULE,
Setting owner isn't necessary any more since v3.11 (commit 9447057eaff8
("platform_device: use a macro instead of platform_driver_register").
> + .of_match_table = pwm_ipq_dt_match,
> + },
> + .probe = ipq_pwm_probe,
> + .remove = ipq_pwm_remove,
> +};
> +
> +module_platform_driver(ipq_pwm_driver);
> +
> +MODULE_LICENSE("Dual BSD/GPL");
> --
> 2.30.2
>
>
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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