Re: [linux-sunxi] [PATCH v2 4/4] ARM: PWM: add allwinner sun8i pwm support.

[Hao Zhang <hao5781286@xxxxxxxxx>]

2018-02-28 9:55 GMT+08:00 André Przywara <andre.przywara@xxxxxxx>:
> Hi,
>
> On 25/02/18 13:53, hao_zhang wrote:
>> This patch add allwinner sun8i pwm support.
>
> Again, the subject line is too generic. Mention the R40?
>
> Can you elaborate here a bit? Mention that is used on the R40, but not
> other sun8i SoCs, for instance. And mention that this is very different
> from the sun4i-pwm device, so justifies a new driver. Possibly mention
> some features? And that we for now just implement a subset of them.

Thanks for reviews, elaborate it next patch:)

>
>>
>> Signed-off-by: hao_zhang <hao5781286@xxxxxxxxx>
>> ---
>>  drivers/pwm/Kconfig     |  10 ++
>>  drivers/pwm/Makefile    |   1 +
>>  drivers/pwm/pwm-sun8i.c | 401 ++++++++++++++++++++++++++++++++++++++++++++++++
>
> I am not too happy with this name, but I guess there are no better
> alternatives, so it's probably OK to keep it.
>
>>  3 files changed, 412 insertions(+)
>>  create mode 100644 drivers/pwm/pwm-sun8i.c
>>
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index 763ee50..7e68d0f 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -444,6 +444,16 @@ config PWM_SUN4I
>>         To compile this driver as a module, choose M here: the module
>>         will be called pwm-sun4i.
>>
>> +config PWM_SUN8I
>> +     tristate "Allwinner PWM SUN8I support"
>> +     depends on ARCH_SUNXI || COMPILE_TEST
>> +     depends on HAS_IOMEM && COMMON_CLK
>> +     help
>> +       Generic PWM framework driver for Allwinner SoCs.
>
> Mmh, not really. So far there is only one SoC using this. Maybe:
>           Driver for the enhanced PWM IP used in some newer Allwinner
>           SoCs.
>
>> +
>> +       To compile this driver as a module, choose M here: the module
>> +       will be called pwm-sun8i.
>> +
>>  config PWM_TEGRA
>>       tristate "NVIDIA Tegra PWM support"
>>       depends on ARCH_TEGRA
>> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
>> index 0258a74..cd6bf40 100644
>> --- a/drivers/pwm/Makefile
>> +++ b/drivers/pwm/Makefile
>> @@ -44,6 +44,7 @@ obj-$(CONFIG_PWM_STM32)             += pwm-stm32.o
>>  obj-$(CONFIG_PWM_STM32_LP)   += pwm-stm32-lp.o
>>  obj-$(CONFIG_PWM_STMPE)              += pwm-stmpe.o
>>  obj-$(CONFIG_PWM_SUN4I)              += pwm-sun4i.o
>> +obj-$(CONFIG_PWM_SUN8I)              += pwm-sun8i.o
>>  obj-$(CONFIG_PWM_TEGRA)              += pwm-tegra.o
>>  obj-$(CONFIG_PWM_TIECAP)     += pwm-tiecap.o
>>  obj-$(CONFIG_PWM_TIEHRPWM)   += pwm-tiehrpwm.o
>> diff --git a/drivers/pwm/pwm-sun8i.c b/drivers/pwm/pwm-sun8i.c
>> new file mode 100644
>> index 0000000..cf23b0a
>> --- /dev/null
>> +++ b/drivers/pwm/pwm-sun8i.c
>> @@ -0,0 +1,401 @@
>> +#include <linux/bitops.h>
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pwm.h>
>> +#include <linux/slab.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/time.h>
>> +#include <linux/regmap.h>
>> +
>> +#define PWM_IRQ_ENABLE_REG   0x0000
>> +#define PCIE(ch)     BIT(ch)
>
> Can you please align those:
> #define PWM_IRQ_ENABLE_REG      0x0000
> #define PCIE(ch)                BIT(ch)
>
> And all those below as well? Which means you might want to insert
> another tab to cater for those longer symbols.

yep, align it is batter :-)

>
>> +
>> +#define PWM_IRQ_STATUS_REG   0x0004
>> +#define PIS(ch)      BIT(ch)
>> +
>> +#define CAPTURE_IRQ_ENABLE_REG       0x0010
>> +#define CFIE(ch)     BIT(ch << 1 + 1)
>> +#define CRIE(ch)     BIT(ch << 1)
>> +
>> +#define CAPTURE_IRQ_STATUS_REG       0x0014
>> +#define CFIS(ch)     BIT(ch << 1 + 1)
>> +#define CRIS(ch)     BIT(ch << 1)
>> +
>> +#define CLK_CFG_REG(ch)      (0x0020 + (ch >> 1) * 4)
>> +#define CLK_SRC      BIT(7)
>> +#define CLK_SRC_BYPASS_SEC   BIT(6)
>> +#define CLK_SRC_BYPASS_FIR   BIT(5)
>> +#define CLK_GATING   BIT(4)
>> +#define CLK_DIV_M    GENMASK(3, 0)
>> +
>> +#define PWM_DZ_CTR_REG(ch)   (0x0030 + (ch >> 1) * 4)
>> +#define PWM_DZ_INTV  GENMASK(15, 8)
>> +#define PWM_DZ_EN    BIT(0)
>> +
>> +#define PWM_ENABLE_REG       0x0040
>> +#define PWM_EN(ch)   BIT(ch)
>> +
>> +#define CAPTURE_ENABLE_REG   0x0044
>> +#define CAP_EN(ch)   BIT(ch)
>> +
>> +#define PWM_CTR_REG(ch)      (0x0060 + ch * 0x20)
>> +#define PWM_PERIOD_RDY       BIT(11)
>> +#define PWM_PUL_START        BIT(10)
>> +#define PWM_MODE     BIT(9)
>> +#define PWM_ACT_STA  BIT(8)
>> +#define PWM_PRESCAL_K        GENMASK(7, 0)
>> +
>> +#define PWM_PERIOD_REG(ch)   (0x0064 + ch * 0x20)
>> +#define PWM_ENTIRE_CYCLE     GENMASK(31, 16)
>> +#define PWM_ACT_CYCLE        GENMASK(15, 0)
>> +
>> +#define PWM_CNT_REG(ch)      (0x0068 + ch * 0x20)
>> +#define PWM_CNT_VAL  GENMASK(15, 0)
>> +
>> +#define CAPTURE_CTR_REG(ch)  (0x006c + ch * 0x20)
>> +#define CAPTURE_CRLF BIT(2)
>> +#define CAPTURE_CFLF BIT(1)
>> +#define CAPINV       BIT(0)
>> +
>> +#define CAPTURE_RISE_REG(ch) (0x0070 + ch * 0x20)
>> +#define CAPTURE_CRLR GENMASK(15, 0)
>> +
>> +#define CAPTURE_FALL_REG(ch) (0x0074 + ch * 0x20)
>> +#define CAPTURE_CFLR GENMASK(15, 0)
>> +
>> +struct sun8i_pwm_data {
>> +     bool has_prescaler_bypass;
>> +     bool has_rdy;
>> +     unsigned int npwm;
>> +};
>
> I believe you don't need this structure. See below.

yep, clock will output directly while bypass has been set,
and equivalent to 50% duty cycles...

>
>> +
>> +struct sun8i_pwm_chip {
>> +     struct pwm_chip chip;
>> +     struct clk *clk;
>> +     void __iomem *base;
>> +     spinlock_t ctrl_lock;
>> +     const struct sun8i_pwm_data *data;
>> +     struct regmap *regmap;
>> +};
>> +
>> +static const u16 div_m_table[] = {
>> +     1,
>> +     2,
>> +     4,
>> +     8,
>> +     16,
>> +     32,
>> +     64,
>> +     128,
>> +     256
>> +};
>
> That looks very much like: "1U << x" to me.

uhmm, i think using table is more explicit and extended...

>
>> +
>> +static inline struct sun8i_pwm_chip *to_sun8i_pwm_chip(struct pwm_chip *chip)
>
> No need for "inline", the compiler knows better. static is enough.

okey :-)

>
>> +{
>> +     return container_of(chip, struct sun8i_pwm_chip, chip);
>> +}
>> +
>> +static u32 sun8i_pwm_read(struct sun8i_pwm_chip *sun8i_pwm,
>> +             unsigned long offset)
>
> Can you please align those continuation lines properly? The first
> character in the new line should be aligned to the first character of
> the first argument. Use tabs first, then fill up with spaces:

Align it next :-)

>
> static u32 sun8i_pwm_read(struct sun8i_pwm_chip *sun8i_pwm,
>                           unsigned long offset)
>
> This applies to the rest of the file as well.
>
>> +{
>> +     u32 val;
>> +
>> +     regmap_read(sun8i_pwm->regmap, offset, &val);
>> +
>> +     return val;
>> +}
>> +
>> +static inline void sun8i_pwm_set_bit(struct sun8i_pwm_chip *sun8i_pwm,
>
> no inline (for those below as well)
>
>> +             unsigned long reg, u32 bit)
>> +{
>> +     regmap_update_bits(sun8i_pwm->regmap, reg, bit, bit);
>> +}
>> +
>> +static inline void sun8i_pwm_clear_bit(struct sun8i_pwm_chip *sun8i_pwm,
>> +             unsigned long reg, u32 bit)
>> +{
>> +     regmap_update_bits(sun8i_pwm->regmap, reg, bit, 0);
>> +}
>> +
>> +static inline void sun8i_pwm_set_value(struct sun8i_pwm_chip *sun8i_pwm,
>> +             unsigned long reg, u32 mask, u32 val)
>> +{
>> +     regmap_update_bits(sun8i_pwm->regmap, reg, mask, val);
>> +}
>> +
>> +static void sun8i_pwm_set_polarity(struct sun8i_pwm_chip *chip, u32 ch,
>> +             enum pwm_polarity polarity)
>> +{
>> +     if (polarity == PWM_POLARITY_NORMAL)
>> +             sun8i_pwm_set_bit(chip, PWM_CTR_REG(ch), PWM_ACT_STA);
>> +     else
>> +             sun8i_pwm_clear_bit(chip, PWM_CTR_REG(ch), PWM_ACT_STA);
>> +}
>> +
>> +static int sun8i_pwm_config(struct sun8i_pwm_chip *sun8i_pwm, u8 ch,
>> +             struct pwm_state *state)
>> +{
>> +     u64 clk_rate, clk_div, val;
>> +     u16 prescaler = 0;
>> +     u8 id = 0;
>> +
>> +     clk_rate = clk_get_rate(sun8i_pwm->clk);
>> +
>> +     if (clk_rate == 24000000)
>> +             sun8i_pwm_clear_bit(sun8i_pwm, CLK_CFG_REG(ch), CLK_SRC);
>> +     else
>> +             sun8i_pwm_set_bit(sun8i_pwm, CLK_CFG_REG(ch), CLK_SRC);
>
> This hardcoded 24MHz looks slightly dodgy and should be replaced with
> some proper code to select the best matching clock, out of a number of
> them given in the DT (see the DT binding mail).
> Without thinking too deeply about it, I guess we try which clocks gives
> the least error for the given configuration. The frequency alone might
> be a good first guide.
> If you can't be bothered with coding this, we might just go ahead with
> the first specified clock and always use this, for now.

Dose the framework support parse 2 or more clk from DT ?
yep, It is better to set the clk automatically

>
>> +
>> +     if (sun8i_pwm->data->has_prescaler_bypass) {
>
> What is this about? I think this is a misunderstanding:
> The bypass bits allows to directly pass on the input clock to the output
> pin, without any actual PWM properties. So if one channel is (by
> chance?) configured for a 50% duty cycle and the same frequency as one
> of the input clocks, you might want to use the bypass bit instead. But I
> don't see many advantages in doing so, so I guess we can ignore it in a
> generic PWM driver.
> Anyway using some hardcoded value from the "data" structure looks just
> wrong to me. I guess you can just remove this, along with the
> has_prescaler_bypass variable from the sun8i_pwm_data structure.

Agree to remove it.

>
>> +             /* pwm output bypass */
>> +             if (ch % 2)
>> +                     sun8i_pwm_set_bit(sun8i_pwm, CLK_CFG_REG(ch),
>> +                                     CLK_SRC_BYPASS_FIR);
>> +             else
>> +                     sun8i_pwm_set_bit(sun8i_pwm, CLK_CFG_REG(ch),
>> +                                     CLK_SRC_BYPASS_SEC);
>> +             return 0;
>> +     }
>> +
>> +     val = state->period * clk_rate;
>> +     do_div(val, NSEC_PER_SEC);
>> +     if (val < 1) {
>> +             dev_err(sun8i_pwm->chip.dev,
>> +                             "Period expects a larger value\n");
>
> Alignment.
> And you might want to hook in here to select a higher frequency input clock.
>
>> +             return -EINVAL;
>> +     }
>> +
>> +     /* calculate and set prescalar, div table, pwn entrie cycle */
>
>                              prescaler             PWM entire
>
> though I believe this "entire cycle" term is an Allwinner invention.
> Wouldn't period be a better term here, also matching the framework?

It seem no...
referent the manual,  "entire cycle" seem means the count of
prescaler_clk(divide by prescaler),
you shoule multiply Tprescaler_clk, then is Tperiod.

>
>> +     clk_div = val;
>> +
>> +     while (clk_div > 65535) {
>> +             prescaler++;
>> +             clk_div = val;
>> +             do_div(clk_div, prescaler + 1);
>> +             do_div(clk_div, div_m_table[id]);
>
>                                 1U << id
>
>> +
>> +             if (prescaler == 255) {
>> +                     prescaler = 0;
>> +                     id++;
>> +                     if (id == 9)
>> +                             return -EINVAL;
>> +             }
>> +     }
>> +
>> +     sun8i_pwm_set_value(sun8i_pwm, PWM_PERIOD_REG(ch),
>> +                     PWM_ENTIRE_CYCLE, clk_div << 16);
>> +     sun8i_pwm_set_value(sun8i_pwm, PWM_CTR_REG(ch),
>> +                     PWM_PRESCAL_K, prescaler << 0);
>> +     sun8i_pwm_set_value(sun8i_pwm, CLK_CFG_REG(ch),
>> +                     CLK_DIV_M, id << 0);
>> +
>> +     /* set duty cycle */
>> +     val = (prescaler + 1) * div_m_table[id] * clk_div;
>
>                                 (1U << id)
>
> You might want to check for the range, though.

Yep :-)

>
>> +     val = state->period;
>> +     do_div(val, clk_div);
>> +     clk_div = state->duty_cycle;
>> +     do_div(clk_div, val);
>> +
>> +     sun8i_pwm_set_value(sun8i_pwm, PWM_PERIOD_REG(ch),
>> +                     PWM_ACT_CYCLE, clk_div << 0);
>> +
>> +     return 0;
>> +}
>> +
>> +static int sun8i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>> +             struct pwm_state *state)
>> +{
>> +     int ret;
>> +     struct sun8i_pwm_chip *sun8i_pwm = to_sun8i_pwm_chip(chip);
>> +     struct pwm_state cstate;
>> +
>> +     pwm_get_state(pwm, &cstate);
>> +     if (!cstate.enabled) {
>> +             ret = clk_prepare_enable(sun8i_pwm->clk);
>> +             if (ret) {
>> +                     dev_err(chip->dev, "Failed to enable PWM clock\n");
>> +                     return ret;
>> +             }
>> +     }
>> +
>> +     spin_lock(&sun8i_pwm->ctrl_lock);
>> +
>> +     if ((cstate.period != state->period) ||
>> +                     (cstate.duty_cycle != state->duty_cycle)) {
>> +             ret = sun8i_pwm_config(sun8i_pwm, pwm->hwpwm, state);
>> +             if (ret) {
>> +                     spin_unlock(&sun8i_pwm->ctrl_lock);
>> +                     dev_err(chip->dev, "Failed to config PWM\n");
>> +                     return ret;
>> +             }
>> +     }
>> +
>> +     if (state->polarity != cstate.polarity)
>> +             sun8i_pwm_set_polarity(sun8i_pwm, pwm->hwpwm, state->polarity);
>> +
>> +     if (state->enabled) {
>> +             sun8i_pwm_set_bit(sun8i_pwm,
>> +                             CLK_CFG_REG(pwm->hwpwm), CLK_GATING);
>> +
>> +             sun8i_pwm_set_bit(sun8i_pwm,
>> +                             PWM_ENABLE_REG, PWM_EN(pwm->hwpwm));
>> +     } else {
>> +             sun8i_pwm_clear_bit(sun8i_pwm,
>> +                             CLK_CFG_REG(pwm->hwpwm), CLK_GATING);
>> +
>> +             sun8i_pwm_clear_bit(sun8i_pwm,
>> +                             PWM_ENABLE_REG, PWM_EN(pwm->hwpwm));
>> +     }
>> +
>> +     spin_unlock(&sun8i_pwm->ctrl_lock);
>> +
>> +     return 0;
>> +}
>> +
>> +static void sun8i_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>> +             struct pwm_state *state)
>> +{
>> +     struct sun8i_pwm_chip *sun8i_pwm = to_sun8i_pwm_chip(chip);
>> +     u64 clk_rate, tmp;
>> +     u32 val;
>> +     u16 clk_div, act_cycle;
>> +     u8 prescal, id;
>
> You might want to add a channel variable to increase readability:
>         int channel = pwm->hwpwm;
>

Okey

>> +
>> +     clk_rate = clk_get_rate(sun8i_pwm->clk);
>> +
>> +     val = sun8i_pwm_read(sun8i_pwm, PWM_CTR_REG(pwm->hwpwm));
>> +     if (PWM_ACT_STA & val)
>> +             state->polarity = PWM_POLARITY_NORMAL;
>> +     else
>> +             state->polarity = PWM_POLARITY_INVERSED;
>> +
>> +     prescal = PWM_PRESCAL_K & val;
>> +
>> +     val = sun8i_pwm_read(sun8i_pwm, PWM_ENABLE_REG);
>> +     if (PWM_EN(pwm->hwpwm) & val)
>> +             state->enabled = true;
>> +     else
>> +             state->enabled = false;
>> +
>> +     val = sun8i_pwm_read(sun8i_pwm, PWM_PERIOD_REG(pwm->hwpwm));
>> +     act_cycle = PWM_ACT_CYCLE & val;
>> +     clk_div = val >> 16;
>> +
>> +     val = sun8i_pwm_read(sun8i_pwm, CLK_CFG_REG(pwm->hwpwm));
>> +     id = CLK_DIV_M & val;
>> +
>> +     tmp = act_cycle * prescal * div_m_table[id] * NSEC_PER_SEC;
>> +     state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
>> +     tmp = clk_div * prescal * div_m_table[id] * NSEC_PER_SEC;
>> +     state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
>> +}
>> +
>> +static const struct regmap_config sun8i_pwm_regmap_config = {
>> +     .reg_bits = 32,
>> +     .reg_stride = 4,
>> +     .val_bits = 32,
>> +     .max_register = CAPTURE_FALL_REG(7),
>> +};
>> +
>> +static const struct pwm_ops sun8i_pwm_ops = {
>> +     .apply = sun8i_pwm_apply,
>> +     .get_state = sun8i_pwm_get_state,
>> +     .owner = THIS_MODULE,
>> +};
>> +
>> +static const struct sun8i_pwm_data sun8i_pwm_data_r40 = {
>> +     .has_prescaler_bypass = false,
>
> This is not needed (see my comment above).

yep.

>
>> +     .has_rdy = true,
>
> And this is not used. Copied from sun4i? Where it interestingly isn't
> used either ;-)
>
>> +     .npwm = 8,
>
> I would really love to see this being moved to the DT (see my other mail
> to Thierry about the generic property).
>
> This would mean you don't need a SoC specific structure at all.

okey.

>
>> +};
>> +
>> +static const struct of_device_id sun8i_pwm_dt_ids[] = {
>> +     {
>> +             .compatible = "allwinner,sun8i-r40-pwm",
>> +             .data = &sun8i_pwm_data_r40,
>> +     },
>> +     {},
>> +};
>> +MODULE_DEVICE_TABLE(of, sun8i_pwm_dt_ids);
>> +
>> +static int sun8i_pwm_probe(struct platform_device *pdev)
>> +{
>> +     struct sun8i_pwm_chip *pwm;
>> +     struct resource *res;
>> +     int ret;
>> +     const struct of_device_id *match;
>> +
>> +     match = of_match_device(sun8i_pwm_dt_ids, &pdev->dev);
>> +     if (!match) {
>> +             dev_err(&pdev->dev, "Error: No device match found\n");
>> +             return -ENODEV;
>> +     }
>> +
>> +     pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
>> +     if (!pwm)
>> +             return -ENOMEM;
>> +
>> +     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     pwm->base = devm_ioremap_resource(&pdev->dev, res);
>> +     if (IS_ERR(pwm->base))
>> +             return PTR_ERR(pwm->base);
>> +
>> +     pwm->regmap = devm_regmap_init_mmio(&pdev->dev, pwm->base,
>> +                     &sun8i_pwm_regmap_config);
>> +     if (IS_ERR(pwm->regmap)) {
>> +             dev_err(&pdev->dev, "Failed to create regmap\n");
>> +             return PTR_ERR(pwm->regmap);
>> +     }
>> +
>> +     pwm->clk = devm_clk_get(&pdev->dev, NULL);
>> +     if (IS_ERR(pwm->clk))
>> +             return PTR_ERR(pwm->clk);
>
> This would need to be extended to get multiple clocks.

okey.

>
>> +
>> +     pwm->data = match->data;
>> +     pwm->chip.dev = &pdev->dev;
>> +     pwm->chip.ops = &sun8i_pwm_ops;
>> +     pwm->chip.base = -1;
>> +     pwm->chip.npwm = pwm->data->npwm;
>
> It should be fairly easy to initialise this from some DT property.
>
> That's it for the my first review round. Haven't checked the actual
> algorithm and bit assignments yet.
> Did you manage to test this?

Sure :-)
All has been tested on my T3 board (compatible V40, R40)
PWM signal is work well observe from oscilloscope.

>
> Cheers,
> Andre.
>
>> +     pwm->chip.of_xlate = of_pwm_xlate_with_flags;
>> +     pwm->chip.of_pwm_n_cells = 3;
>> +
>> +     spin_lock_init(&pwm->ctrl_lock);
>> +
>> +     ret = pwmchip_add(&pwm->chip);
>> +     if (ret < 0) {
>> +             dev_err(&pdev->dev, "Failed to add PWM chip: %d\n", ret);
>> +             return ret;
>> +     }
>> +
>> +     platform_set_drvdata(pdev, pwm);
>> +
>> +     return 0;
>> +}
>> +
>> +static int sun8i_pwm_remove(struct platform_device *pdev)
>> +{
>> +     struct sun8i_pwm_chip *pwm = platform_get_drvdata(pdev);
>> +
>> +     return pwmchip_remove(&pwm->chip);
>> +}
>> +
>> +static struct platform_driver sun8i_pwm_driver = {
>> +     .driver = {
>> +             .name = "sun8i-pwm",
>> +             .of_match_table = sun8i_pwm_dt_ids,
>> +     },
>> +     .probe = sun8i_pwm_probe,
>> +     .remove = sun8i_pwm_remove,
>> +};
>> +module_platform_driver(sun8i_pwm_driver);
>> +
>> +MODULE_ALIAS("platform: sun8i-pwm");
>> +MODULE_AUTHOR("Hao Zhang <hao5781286@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("Allwinner sun8i PWM driver");
>> +MODULE_LICENSE("GPL v2");
>>
>
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