[PATCH 2/2] pwm: add ZTE ZX PWM device driver

Thierry Reding
2017-07-25T11:53:43Z

On Thu, Jun 29, 2017 at 10:54:34AM +0800, Shawn Guo wrote:
> From: Shawn Guo <shawn.guo@linaro.org>
>
> It adds PWM device driver for ZTE ZX family SoCs. The PWM controller
> supports 4 devices with polarity configuration.
>
> The driver has been tested with pwm-regulator support to scale core
> voltage via cpufreq.
>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> ---
> drivers/pwm/Kconfig | 9 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-zx.c | 244 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 254 insertions(+)
> create mode 100644 drivers/pwm/pwm-zx.c

Hi Shawn,

This is close to perfect. Two minor things, see below.

> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 313c10789ca2..e98175331a69 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -500,4 +500,13 @@ config PWM_VT8500
> To compile this driver as a module, choose M here: the module
> will be called pwm-vt8500.
>
> +config PWM_ZX
> + tristate "ZTE ZX PWM support"
> + depends on ARCH_ZX
> + help
> + Generic PWM framework driver for ZTE ZX family SoCs.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called pwm-zx.
> +
> endif
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 93da1f79a3b8..75ab74094d7b 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -49,3 +49,4 @@ obj-$(CONFIG_PWM_TIPWMSS) += pwm-tipwmss.o
> obj-$(CONFIG_PWM_TWL) += pwm-twl.o
> obj-$(CONFIG_PWM_TWL_LED) += pwm-twl-led.o
> obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o
> +obj-$(CONFIG_PWM_ZX) += pwm-zx.o
> diff --git a/drivers/pwm/pwm-zx.c b/drivers/pwm/pwm-zx.c
> new file mode 100644
> index 000000000000..5c81c2ddc0a9
> --- /dev/null
> +++ b/drivers/pwm/pwm-zx.c
> @@ -0,0 +1,244 @@
> +/*
> + * Copyright (C) 2017 Sanechips Technology Co., Ltd.
> + * Copyright 2017 Linaro Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/slab.h>
> +
> +#define ZX_PWM_MODE 0x0
> +#define ZX_PWM_CLKDIV_MASK GENMASK(11, 2)
> +#define ZX_PWM_CLKDIV(x) (((x) << 8) & ZX_PWM_CLKDIV_MASK)
> +#define ZX_PWM_POLAR BIT(1)
> +#define ZX_PWM_EN BIT(0)
> +#define ZX_PWM_PERIOD 0x4
> +#define ZX_PWM_DUTY 0x8
> +
> +#define ZX_PWM_CLKDIV_MAX 1023
> +#define ZX_PWM_PERIOD_MAX 65535
> +
> +struct zx_pwm_chip {
> + struct pwm_chip chip;
> + struct clk *pclk;
> + struct clk *wclk;
> + void __iomem *base;
> +};
> +
> +#define to_zx_pwm_chip(_chip) container_of(_chip, struct zx_pwm_chip, chip)

Please use a static inline function for this. That way diagnostic
messages from the compiler make more sense.

[...]
> +static const struct pwm_ops zx_pwm_ops = {
> + .config = zx_pwm_config,
> + .enable = zx_pwm_enable,
> + .disable = zx_pwm_disable,
> + .set_polarity = zx_pwm_set_polarity,
> + .owner = THIS_MODULE,
> +};

Please convert this to implement the atomic PWM callbacks (->apply() and
->get_state()).

Thanks,
Thierry
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