Hi Rahul,
I just have some small nitpicks, see below:
On Wed, 2020-09-09 at 15:51 +0800, Rahul Tanwar wrote:
> Intel Lightning Mountain(LGM) SoC contains a PWM fan controller.
> This PWM controller does not have any other consumer, it is a
> dedicated PWM controller for fan attached to the system. Add
> driver for this PWM fan controller.
>
> Signed-off-by: Rahul Tanwar <rahul.tanwar@xxxxxxxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
> ---
> drivers/pwm/Kconfig | 11 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-intel-lgm.c | 253 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 265 insertions(+)
> create mode 100644 drivers/pwm/pwm-intel-lgm.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 7dbcf6973d33..4949c51fe90b 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -232,6 +232,17 @@ config PWM_IMX_TPM
> To compile this driver as a module, choose M here: the module
> will be called pwm-imx-tpm.
>
> +config PWM_INTEL_LGM
> + tristate "Intel LGM PWM support"
> + depends on HAS_IOMEM
> + depends on (OF && X86) || COMPILE_TEST
> + select REGMAP_MMIO
> + help
> + Generic PWM fan controller driver for LGM SoC.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called pwm-intel-lgm.
> +
> 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 2c2ba0a03557..e9431b151694 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_PWM_IMG) += pwm-img.o
> obj-$(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_IQS620A) += pwm-iqs620a.o
> obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o
> obj-$(CONFIG_PWM_LP3943) += pwm-lp3943.o
> diff --git a/drivers/pwm/pwm-intel-lgm.c b/drivers/pwm/pwm-intel-lgm.c
> new file mode 100644
> index 000000000000..8e9f8cd3b7fb
> --- /dev/null
> +++ b/drivers/pwm/pwm-intel-lgm.c
> @@ -0,0 +1,253 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Intel Corporation.
> + *
> + * Limitations:
> + * - The hardware supports fixed period which is dependent on 2/3 or 4
> + * wire fan mode.
> + * - Supports normal polarity. Does not support changing polarity.
> + * - When PWM is disabled, output of PWM will become 0(inactive). It doesn't
> + * keep track of running period.
> + * - When duty cycle is changed, PWM output may be a mix of previous setting
> + * and new setting for the first period. From second period, the output is
> + * based on new setting.
> + * - It is a dedicated PWM fan controller. There are no other consumers for
> + * this PWM controller.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +
> +#define LGM_PWM_FAN_CON0 0x0
> +#define LGM_PWM_FAN_EN_EN BIT(0)
> +#define LGM_PWM_FAN_EN_DIS 0x0
> +#define LGM_PWM_FAN_EN_MSK BIT(0)
> +#define LGM_PWM_FAN_MODE_2WIRE 0x0
> +#define LGM_PWM_FAN_MODE_MSK BIT(1)
> +#define LGM_PWM_FAN_DC_MSK GENMASK(23, 16)
> +
> +#define LGM_PWM_FAN_CON1 0x4
> +#define LGM_PWM_FAN_MAX_RPM_MSK GENMASK(15, 0)
> +
> +#define LGM_PWM_MAX_RPM (BIT(16) - 1)
> +#define LGM_PWM_DEFAULT_RPM 4000
> +#define LGM_PWM_MAX_DUTY_CYCLE (BIT(8) - 1)
> +
> +#define LGM_PWM_DC_BITS 8
> +
> +#define LGM_PWM_PERIOD_2WIRE_NS (40 * NSEC_PER_MSEC)
> +
> +struct lgm_pwm_chip {
> + struct pwm_chip chip;
> + struct regmap *regmap;
> + struct clk *clk;
> + struct reset_control *rst;
> + u32 period;
> +};
> +
> +static inline struct lgm_pwm_chip *to_lgm_pwm_chip(struct pwm_chip *chip)
> +{
> + return container_of(chip, struct lgm_pwm_chip, chip);
> +}
> +
> +static int lgm_pwm_enable(struct pwm_chip *chip, bool enable)
> +{
> + struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
> + struct regmap *regmap = pc->regmap;
> +
> + return regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_EN_MSK,
> + enable ? LGM_PWM_FAN_EN_EN : LGM_PWM_FAN_EN_DIS);
> +}
> +
> +static int lgm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
> + u32 duty_cycle, val;
> + int ret;
> +
> + /*
> + * The hardware only supports
> + * normal polarity and fixed period.
> + */
That comment could be put on a single line.
> + if (state->polarity != PWM_POLARITY_NORMAL || state->period < pc->period)
> + return -EINVAL;
> +
> + if (!state->enabled)
> + return lgm_pwm_enable(chip, 0);
> +
> + duty_cycle = min_t(u64, state->duty_cycle, pc->period);
> + val = duty_cycle * LGM_PWM_MAX_DUTY_CYCLE / pc->period;
> +
> + ret = regmap_update_bits(pc->regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_DC_MSK,
> + FIELD_PREP(LGM_PWM_FAN_DC_MSK, val));
> + if (ret)
> + return ret;
> +
> + return lgm_pwm_enable(chip, 1);
> +}
> +
> +static void lgm_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> + struct pwm_state *state)
> +{
> + struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
> + u32 duty, val;
> +
> + state->enabled = regmap_test_bits(pc->regmap, LGM_PWM_FAN_CON0,
> + LGM_PWM_FAN_EN_EN);
> + state->polarity = PWM_POLARITY_NORMAL;
> + state->period = pc->period; /* fixed period */
> +
> + regmap_read(pc->regmap, LGM_PWM_FAN_CON0, &val);
> + duty = FIELD_GET(LGM_PWM_FAN_DC_MSK, val);
> + state->duty_cycle = DIV_ROUND_UP(duty * pc->period, LGM_PWM_MAX_DUTY_CYCLE);
> +}
> +
> +static const struct pwm_ops lgm_pwm_ops = {
> + .get_state = lgm_pwm_get_state,
> + .apply = lgm_pwm_apply,
> + .owner = THIS_MODULE,
> +};
> +
> +static void lgm_pwm_init(struct lgm_pwm_chip *pc)
> +{
> + struct regmap *regmap = pc->regmap;
> + u32 con0_val;
> +
> + con0_val = FIELD_PREP(LGM_PWM_FAN_MODE_MSK, LGM_PWM_FAN_MODE_2WIRE);
> + pc->period = LGM_PWM_PERIOD_2WIRE_NS;
> + regmap_update_bits(regmap, LGM_PWM_FAN_CON1, LGM_PWM_FAN_MAX_RPM_MSK,
> + LGM_PWM_DEFAULT_RPM);
> + regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_MODE_MSK,
> + con0_val);
> +}
> +
> +static const struct regmap_config lgm_pwm_regmap_config = {
> + .reg_bits = 32,
> + .reg_stride = 4,
> + .val_bits = 32,
> +};
> +
> +static void lgm_clk_disable(void *data)
> +{
> + struct lgm_pwm_chip *pc = data;
> +
> + clk_disable_unprepare(pc->clk);
> +}
> +
> +static int lgm_clk_enable(struct device *dev, struct lgm_pwm_chip *pc)
> +{
> + int ret;
> +
> + ret = clk_prepare_enable(pc->clk);
> + if (ret)
> + return ret;
> +
> + return devm_add_action_or_reset(dev, lgm_clk_disable, pc);
> +}
> +
> +static void lgm_reset_control_assert(void *data)
> +{
> + struct lgm_pwm_chip *pc = data;
> +
> + reset_control_assert(pc->rst);
> +}
> +
> +static int lgm_reset_control_deassert(struct device *dev, struct lgm_pwm_chip *pc)
> +{
> + int ret;
> +
> + ret = reset_control_deassert(pc->rst);
> + if (ret)
> + return ret;
> +
> + return devm_add_action_or_reset(dev, lgm_reset_control_assert, pc);
> +}
> +
> +static int lgm_pwm_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct lgm_pwm_chip *pc;
> + void __iomem *io_base;
> + int ret;
> +
> + pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
> + if (!pc)
> + return -ENOMEM;
> +
> + io_base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(io_base))
> + return PTR_ERR(io_base);
> +
> + pc->regmap = devm_regmap_init_mmio(dev, io_base, &lgm_pwm_regmap_config);
> + if (IS_ERR(pc->regmap))
> + return dev_err_probe(dev, PTR_ERR(pc->regmap),
> + "failed to init register map\n");
> +
> + pc->rst = devm_reset_control_get_exclusive(dev, NULL);
> + if (IS_ERR(pc->rst))
> + return dev_err_probe(dev, PTR_ERR(pc->rst),
> + "failed to get reset control\n");
> +
> + ret = lgm_reset_control_deassert(dev, pc);
> + if (ret)
> + return dev_err_probe(dev, ret, "cannot deassert reset control\n");
I would request all resources before deasserting the reset, that way
-EPROBE_DEFER due to missing clocks would keep the controller in reset.
> + pc->clk = devm_clk_get(dev, NULL);
> + if (IS_ERR(pc->clk))
> + return dev_err_probe(dev, PTR_ERR(pc->clk), "failed to get clock\n");
> +
> + ret = lgm_clk_enable(dev, pc);
> + if (ret) {
> + dev_err(dev, "failed to enable clock\n");
> + return ret;
> + }
> +
> + pc->chip.dev = dev;
> + pc->chip.ops = &lgm_pwm_ops;
> + pc->chip.npwm = 1;
> +
> + lgm_pwm_init(pc);
> +
> + ret = pwmchip_add(&pc->chip);
> + if (ret < 0) {
> + dev_err(dev, "failed to add PWM chip: %pe\n", ERR_PTR(ret));
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, pc);
> + return 0;
> +}
> +
> +static int lgm_pwm_remove(struct platform_device *pdev)
> +{
> + struct lgm_pwm_chip *pc = platform_get_drvdata(pdev);
> + int ret;
> +
> + ret = pwmchip_remove(&pc->chip);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
You could just
return pwmchip_remove(&pc->chip);
here.
regards
Philipp
