Hi Uwe,
On 14/7/2020 3:10 am, Uwe Kleine-König wrote:
> Hello,
>
> On Tue, Jun 30, 2020 at 03:55:32PM +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>
>> ---
>> drivers/pwm/Kconfig | 11 ++
>> drivers/pwm/Makefile | 1 +
>> drivers/pwm/pwm-intel-lgm.c | 266 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 278 insertions(+)
>> create mode 100644 drivers/pwm/pwm-intel-lgm.c
>>
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index cb8d739067d2..3486edab09c4 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 OF && HAS_IOMEM
>> + depends on 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 a59c710e98c7..db154a6b4f51 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..fddfedd56fc3
>> --- /dev/null
>> +++ b/drivers/pwm/pwm-intel-lgm.c
>> @@ -0,0 +1,266 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2020 Intel Corporation.
>> + *
>> + * Notes & Limitations:
> I'd like to have this "Limitations:" only to make it easily greppable.
>
>> + * - 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/of_device.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_4WIRE 0x1
>> +#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_NSECS 40000000
>> +#define LGM_PWM_PERIOD_4WIRE_NSECS 40000
>> +
>> +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;
>> +
>> + regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_EN_MSK,
>> + enable ? LGM_PWM_FAN_EN_EN : LGM_PWM_FAN_EN_DIS);
> regmap_update_bits has a return value. I think it is supposed to be
> checked.
>
>> +
>> + return 0;
>> +}
>> +
>> +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;
>> + unsigned int period;
>> +
>> + if (!state->enabled) {
>> + lgm_pwm_enable(chip, 0);
>> + return 0;
>> + }
>> +
>> + period = min_t(u64, state->period, pc->period);
>> +
>> + if (state->polarity != PWM_POLARITY_NORMAL ||
>> + period < pc->period)
>> + return -EINVAL;
> This check looks wrong. If you refuse period < pc->period there isn't
> much configuration possible.
>
>> + duty_cycle = min_t(u32, state->duty_cycle, period);
> This is wrong. Consider state->duty_cycle = 0x100000001 (once it is an
> u64).
>
>> + /* reg_value = duty_ns * LGM_PWM_MAX_DUTY_CYCLE(0xff) / period_ns */
>> + val = duty_cycle * LGM_PWM_MAX_DUTY_CYCLE / period;
> The comment is little helpful.
>
>> + regmap_update_bits(pc->regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_DC_MSK,
>> + FIELD_PREP(LGM_PWM_FAN_DC_MSK, val));
>> +
>> + if (state->enabled)
>> + lgm_pwm_enable(chip, 1);
>> +
>> + return 0;
>> +}
>> +
>> +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 device *dev = pc->chip.dev;
>> + struct regmap *regmap = pc->regmap;
>> + u32 max_rpm, fan_wire, con0_val, con0_mask;
>> +
>> + if (device_property_read_u32(dev, "intel,fan-wire", &fan_wire))
>> + fan_wire = 2; /* default is 2 wire mode */
>> +
>> + con0_mask = LGM_PWM_FAN_MODE_MSK;
>> +
>> + switch (fan_wire) {
>> + case 4:
>> + con0_val = FIELD_PREP(LGM_PWM_FAN_MODE_MSK, LGM_PWM_FAN_MODE_4WIRE);
>> + pc->period = LGM_PWM_PERIOD_4WIRE_NSECS;
>> + break;
>> + default:
>> + /* default is 2wire mode */
>> + con0_val = FIELD_PREP(LGM_PWM_FAN_MODE_MSK, LGM_PWM_FAN_MODE_2WIRE);
>> + pc->period = LGM_PWM_PERIOD_2WIRE_NSECS;
>> + break;
>> + }
>> +
>> + if (device_property_read_u32(dev, "intel,max-rpm", &max_rpm))
>> + max_rpm = LGM_PWM_DEFAULT_RPM;
>> +
>> + max_rpm = min_t(u32, max_rpm, LGM_PWM_MAX_RPM);
>> + if (max_rpm == 0)
>> + max_rpm = LGM_PWM_DEFAULT_RPM;
>> +
>> + regmap_update_bits(regmap, LGM_PWM_FAN_CON1, LGM_PWM_FAN_MAX_RPM_MSK, max_rpm);
>> + regmap_update_bits(regmap, LGM_PWM_FAN_CON0, con0_mask, con0_val);
>> +}
>> +
>> +static const struct regmap_config lgm_pwm_regmap_config = {
>> + .reg_bits = 32,
>> + .reg_stride = 4,
>> + .val_bits = 32,
>> +};
>> +
>> +static int lgm_pwm_probe(struct platform_device *pdev)
>> +{
>> + struct lgm_pwm_chip *pc;
>> + struct device *dev = &pdev->dev;
>> + 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)) {
>> + ret = PTR_ERR(pc->regmap);
>> + if (ret != -EPROBE_DEFER)
>> + dev_err(dev, "failed to init register map: %pe\n",
>> + pc->regmap);
>> + return ret;
>> + }
>> +
>> + pc->clk = devm_clk_get(dev, NULL);
>> + if (IS_ERR(pc->clk)) {
>> + ret = PTR_ERR(pc->clk);
>> + if (ret != -EPROBE_DEFER)
>> + dev_err(dev, "failed to get clock: %pe\n", pc->clk);
>> + return ret;
>> + }
>> +
>> + pc->rst = devm_reset_control_get_exclusive(dev, NULL);
>> + if (IS_ERR(pc->rst)) {
>> + ret = PTR_ERR(pc->rst);
>> + if (ret != -EPROBE_DEFER)
>> + dev_err(dev, "failed to get reset control: %pe\n",
>> + pc->rst);
>> + return ret;
>> + }
>> +
>> + ret = reset_control_deassert(pc->rst);
>> + if (ret) {
>> + if (ret != -EPROBE_DEFER)
>> + dev_err(dev, "cannot deassert reset control: %pe\n",
>> + ERR_PTR(ret));
>> + return ret;
>> + }
>> +
>> + ret = clk_prepare_enable(pc->clk);
>> + if (ret) {
>> + dev_err(dev, "failed to enable clock\n");
> reset_control_assert missing here.
>
>> + 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));
>> + clk_disable_unprepare(pc->clk);
>> + reset_control_assert(pc->rst);
>> + 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;
>> +
>> + clk_disable_unprepare(pc->clk);
>> + reset_control_assert(pc->rst);
> Please swap the two previous lines to match the error patch of .probe.
>
>> +
>> + return 0;
>> +}
>
Given the fact that this is a dedicated PWM fan controller with no other
PWM consumer, do you think that this driver belongs to drivers/hwmon
instead of drivers/pwm? Thanks.
Regards,
Rahul
