On Wed, Jun 05, 2013 at 11:18:13PM +0200, Tomasz Figa wrote:
> This patch introduces new Samsung PWM driver, which uses Samsung
> PWM/timer master driver to control shared parts of the hardware.
>
> Signed-off-by: Tomasz Figa <tomasz.figa@xxxxxxxxx>
Sorry for jumping in so late, I've been busy with other things lately.
> ---
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-samsung.c | 528 ++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 529 insertions(+)
> create mode 100644 drivers/pwm/pwm-samsung.c
>
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 229a599..833c3ac 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
> obj-$(CONFIG_PWM_PUV3) += pwm-puv3.o
> obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
> obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung-legacy.o
> +obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
> obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o
> obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o
> obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o
> diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
> new file mode 100644
> index 0000000..61bed3d
> --- /dev/null
> +++ b/drivers/pwm/pwm-samsung.c
> @@ -0,0 +1,528 @@
> +/* drivers/pwm/pwm-samsung.c
Nit: this line can be dropped. It serves no purpose.
> + *
> + * Copyright (c) 2007 Ben Dooks
> + * Copyright (c) 2008 Simtec Electronics
> + * Ben Dooks <ben@xxxxxxxxxxxx>, <ben-linux@xxxxxxxxx>
> + * Copyright (c) 2013 Tomasz Figa <tomasz.figa@xxxxxxxxx>
> + *
> + * PWM driver for Samsung SoCs
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License.
> +*/
Nit: the */ should align with the * above.
> +struct samsung_pwm_channel {
> + unsigned long period_ns;
> + unsigned long duty_ns;
> + unsigned long tin_ns;
> +};
> +
> +struct samsung_pwm_chip {
> + struct pwm_chip chip;
> + struct samsung_pwm_variant variant;
> + struct samsung_pwm_channel channels[SAMSUNG_PWM_NUM];
The new driver for Renesas did something similar, but I want to
discourage storing per-channel data within the chip structure.
The PWM framework provides a way to store this information along with
the PWM device (see pwm_{set,get}_chip_data()).
> +
> + void __iomem *base;
> + struct clk *base_clk;
> + struct clk *tclk0;
> + struct clk *tclk1;
> +};
> +#define to_samsung_pwm_chip(chip) \
> + container_of(chip, struct samsung_pwm_chip, chip)
Can you turn this into a static inline function please?
> +#ifndef CONFIG_CLKSRC_SAMSUNG_PWM
> +static DEFINE_SPINLOCK(samsung_pwm_lock);
> +#endif
Why is this lock global? Shouldn't it more correctly be part of
samsung_pwm_chip?
> +static void pwm_samsung_set_divisor(struct samsung_pwm_chip *pwm,
> + unsigned int channel, u8 divisor)
Nit: please align arguments on subsequent lines with the first argument
of the first line. There's many more of these but I haven't mentioned
them all explicitly.
> +static inline int pwm_samsung_is_tdiv(struct samsung_pwm_chip *chip,
Any particular reason for making this inline?
> +static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
> + int duty_ns, int period_ns)
> +{
> + struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
> + struct samsung_pwm_channel *chan = &our_chip->channels[pwm->hwpwm];
> + unsigned long tin_ns = chan->tin_ns;
> + unsigned int tcon_chan = pwm->hwpwm;
> + unsigned long tin_rate;
> + unsigned long period;
> + unsigned long flags;
> + unsigned long tcnt;
Many of these unsigned long variable could be declared on a single line
to make the function shorter.
> + long tcmp;
> + u32 tcon;
> +
> + /* We currently avoid using 64bit arithmetic by using the
> + * fact that anything faster than 1Hz is easily representable
> + * by 32bits. */
Can you turn these into proper block-style comments? Like so:
/*
* We currently...
* ...
* by 32 bits.
*/
> + if (period_ns > NSEC_PER_SEC || duty_ns > NSEC_PER_SEC)
> + return -ERANGE;
Note that technically you only need to check period_ns because the core
already ensures that duty_ns <= period_ns.
> +static int pwm_samsung_set_polarity(struct pwm_chip *chip,
> + struct pwm_device *pwm, enum pwm_polarity polarity)
> +{
> + struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
> + unsigned int channel = pwm->hwpwm;
> + unsigned long flags;
> + u32 tcon;
> +
> + if (channel > 0)
> + ++channel;
You have to repeat that in quite a few places, so I wonder if it'd make
sense to wrap it into a function and add a comment about why the
increment is necessary.
> +static struct pwm_ops pwm_samsung_ops = {
"static const" please.
> +#ifdef CONFIG_OF
> +static const struct samsung_pwm_variant s3c24xx_variant = {
> + .bits = 16,
> + .div_base = 1,
> + .has_tint_cstat = false,
> + .tclk_mask = (1 << 4),
> +};
> +
> +static const struct samsung_pwm_variant s3c64xx_variant = {
> + .bits = 32,
> + .div_base = 0,
> + .has_tint_cstat = true,
> + .tclk_mask = (1 << 7) | (1 << 6) | (1 << 5),
> +};
> +
> +static const struct samsung_pwm_variant s5p64x0_variant = {
> + .bits = 32,
> + .div_base = 0,
> + .has_tint_cstat = true,
> + .tclk_mask = 0,
> +};
> +
> +static const struct samsung_pwm_variant s5p_variant = {
> + .bits = 32,
> + .div_base = 0,
> + .has_tint_cstat = true,
> + .tclk_mask = (1 << 5),
> +};
> +
> +static const struct of_device_id samsung_pwm_matches[] = {
> + { .compatible = "samsung,s3c2410-pwm", .data = &s3c24xx_variant },
> + { .compatible = "samsung,s3c6400-pwm", .data = &s3c64xx_variant },
> + { .compatible = "samsung,s5p6440-pwm", .data = &s5p64x0_variant },
> + { .compatible = "samsung,s5pc100-pwm", .data = &s5p_variant },
> + { .compatible = "samsung,exynos4210-pwm", .data = &s5p64x0_variant },
> + {},
> +};
> +#endif
> +
> +static int pwm_samsung_parse_dt(struct samsung_pwm_chip *chip)
> +{
> + struct device_node *np = chip->chip.dev->of_node;
> + const struct of_device_id *match;
> + struct property *prop;
> + const __be32 *cur;
> + u32 val;
> +
> + match = of_match_node(samsung_pwm_matches, np);
> + if (!match)
> + return -ENODEV;
> +
> + memcpy(&chip->variant, match->data, sizeof(chip->variant));
> +
> + of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
> + if (val >= SAMSUNG_PWM_NUM) {
> + pr_warning("%s: invalid channel index in samsung,pwm-outputs property\n",
> + __func__);
> + continue;
> + }
> + chip->variant.output_mask |= 1 << val;
Could the output_mask be moved to the struct samsung_pwm_chip instead?
The reason I ask is because it would allow you to make the variant
constant throughout the driver.
> +static int pwm_samsung_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct samsung_pwm_chip *chip;
> + struct resource *res;
> + int ret;
> +
> + chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> + if (chip == NULL) {
> + dev_err(dev, "failed to allocate driver data\n");
> + return -ENOMEM;
> + }
> +
> + chip->chip.dev = &pdev->dev;
> + chip->chip.ops = &pwm_samsung_ops;
> + chip->chip.base = -1;
> + chip->chip.npwm = SAMSUNG_PWM_NUM;
> +
> + if (pdev->dev.of_node) {
Maybe add an IS_ENABLED(CONFIG_OF) check here? That'd allow all OF-
related code to be thrown away if OF isn't selected.
> + ret = pwm_samsung_parse_dt(chip);
> + if (ret)
> + return ret;
> +
> + chip->chip.of_xlate = of_pwm_xlate_with_flags;
> + chip->chip.of_pwm_n_cells = 3;
> + } else {
> + if (!pdev->dev.platform_data) {
> + dev_err(&pdev->dev, "no platform data specified\n");
> + return -EINVAL;
> + }
> +
> + memcpy(&chip->variant, pdev->dev.platform_data,
> + sizeof(chip->variant));
> + }
Obviously this needs some modification in order for the variant to
become constant. But I think you can easily do so by making the driver
match using the platform_driver's id_table field, similar to how the
matching is done for OF.
> + chip->base = devm_request_and_ioremap(&pdev->dev, res);
> + if (!chip->base) {
> + dev_err(&pdev->dev, "failed to request and map registers\n");
> + return -ENOMEM;
> + }
devm_request_and_ioremap() is now deprecated and in the process of being
removed. You should use devm_ioremap_resource() instead.
> +
> + chip->base_clk = devm_clk_get(&pdev->dev, "timers");
> + if (IS_ERR(chip->base_clk)) {
> + dev_err(dev, "failed to get timer base clk\n");
> + return PTR_ERR(chip->base_clk);
> + }
> + clk_prepare_enable(chip->base_clk);
You need to check the return value of clk_prepare_enable(). And if I was
very pedantic, there should be a blank line before this one.
> + ret = pwmchip_add(&chip->chip);
> + if (ret < 0) {
> + dev_err(dev, "failed to register pwm\n");
"failed to register PWM chip" please.
> + goto err_clk_disable;
> + }
> +
> + dev_info(dev, "base_clk at %lu, tclk0 at %lu, tclk1 at %lu\n",
> + clk_get_rate(chip->base_clk),
> + !IS_ERR(chip->tclk0) ? clk_get_rate(chip->tclk0) : 0,
> + !IS_ERR(chip->tclk1) ? clk_get_rate(chip->tclk1) : 0);
> +
> + platform_set_drvdata(pdev, chip);
> +
> + return 0;
> +
> +err_clk_disable:
> + clk_disable_unprepare(chip->base_clk);
> +
> + return ret;
There's only a single case where this can actually happen, so I don't
think you need the label here. Just put the clk_disable_unprepare() call
and the return statement where you jump to the label.
> +#ifdef CONFIG_PM
I think this should really be CONFIG_PM_SLEEP.
> +static struct dev_pm_ops pwm_samsung_pm_ops = {
"static const" please.
Thierry
Attachment:
pgpNp6YUIow9e.pgp
Description: PGP signature
