[PATCH 1/4] pwm: Add Allwinner SoC support
Maxime Ripard
maxime.ripard at free-electrons.com
Mon Mar 31 13:35:37 EDT 2014
On Mon, Mar 31, 2014 at 02:07:26PM +0200, Alexandre Belloni wrote:
> This adds a generic PWM framework driver for the PWM controller
> found on Allwinner SoCs.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni at free-electrons.com>
> ---
> drivers/pwm/Kconfig | 9 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-sunxi.c | 325 ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 335 insertions(+)
> create mode 100644 drivers/pwm/pwm-sunxi.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 22f2f2857b82..f7381def0fd2 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -187,6 +187,15 @@ config PWM_SPEAR
> To compile this driver as a module, choose M here: the module
> will be called pwm-spear.
>
> +config PWM_SUNXI
> + tristate "Allwinner PWM support"
> + depends on ARCH_SUNXI
> + help
> + Generic PWM framework driver for Allwinner SoCs.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called pwm-sunxi.
> +
> config PWM_TEGRA
> tristate "NVIDIA Tegra PWM support"
> depends on ARCH_TEGRA
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index d8906ec69976..e110259b6c03 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
> obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o
> obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
> obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o
> +obj-$(CONFIG_PWM_SUNXI) += pwm-sunxi.o
> obj-$(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-sunxi.c b/drivers/pwm/pwm-sunxi.c
> new file mode 100644
> index 000000000000..be39abee0a24
> --- /dev/null
> +++ b/drivers/pwm/pwm-sunxi.c
> @@ -0,0 +1,325 @@
> +/*
> + * Driver for Allwinner Pulse Width Modulation Controller
> + *
> + * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni at free-electrons.com>
> + *
> + * Licensed under GPLv2.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.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>
> +
> +#define PWM_CTRL_REG 0x0
> +
> +#define PWM_CH_PRD_BASE 0x4
> +#define PWM_CH_PRD_OFF 0x4
> +#define PWM_CH_PRD(x) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFF * x)
> +
> +#define PWMCH_OFFSET 15
^ That looks odd.
> +#define PWM_PRESCAL_MASK (BIT(0)|BIT(1)|BIT(2)|BIT(3))
> +#define PWM_PRESCAL_OFF 0
> +#define PWM_EN BIT(4)
> +#define PWM_ACT_STATE BIT(5)
> +#define PWM_CLK_GATING BIT(6)
> +#define PWM_MODE BIT(7)
> +#define PWM_PULSE BIT(8)
> +#define PWM_BYPASS BIT(9)
> +
> +#define PWM_RDY_BASE 28
> +#define PWM_RDY_OFF 1
> +#define PWM_RDY(x) BIT(PWM_RDY_BASE + PWM_RDY_OFF * x)
> +
> +#define PWM_PRD_ACT_MASK 0xFF
> +#define PWM_PRD(x) (x << 16)
> +#define PWM_PRD_MASK 0xFF
> +
> +#define BIT_CH(bit, chan) (bit << (chan * PWMCH_OFFSET))
> +
> +u32 prescal_table[] = { 120, 180, 240, 360, 480, 0, 0, 0,
> + 12000, 24000, 36000, 48000, 72000,
> + 0, 0, 1 };
> +
> +struct sunxi_pwm_data {
> + bool has_rdy;
> +};
> +
> +struct sunxi_pwm_chip {
> + struct pwm_chip chip;
> + struct clk *clk;
> + void __iomem *base;
> + const struct sunxi_pwm_data *data;
> +};
> +
> +#define to_sunxi_pwm_chip(chip) container_of(chip, struct sunxi_pwm_chip, chip)
> +
> +static inline u32 sunxi_pwm_readl(struct sunxi_pwm_chip *chip,
> + unsigned long offset)
> +{
> + return readl_relaxed(chip->base + offset);
> +}
> +
> +static inline void sunxi_pwm_writel(struct sunxi_pwm_chip *chip,
> + unsigned long offset, unsigned long val)
> +{
> + writel_relaxed(val, chip->base + offset);
> +}
Do you have a reason to not use plain readl/writel?
> +static int sunxi_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> + int duty_ns, int period_ns)
> +{
> + struct sunxi_pwm_chip *sunxi_pwm = to_sunxi_pwm_chip(chip);
> + u32 clk_rate, prd, dty;
> + u64 div;
> + u32 val, clk_gate;
> + int i, ret;
> +
> + clk_rate = clk_get_rate(sunxi_pwm->clk);
> +
> +
You can drop the extra line here.
> + /* First, test without any divider */
> + i = PWM_PRESCAL_MASK;
> + div = clk_rate * period_ns;
> + do_div(div, 1000000000);
> + if (div > PWM_PRD_MASK) {
> + /* Then go up from the first divider */
> + for (i = 0; i < PWM_PRESCAL_MASK; i++) {
> + if (!prescal_table[i])
> + continue;
> + div = clk_rate / prescal_table[i];
> + div = div * period_ns;
> + do_div(div, 1000000000);
> + if (div <= PWM_PRD_MASK)
> + break;
> + }
> + }
> +
> + if (div > PWM_PRD_MASK) {
> + dev_err(chip->dev, "prescaler exceeds the maximum value\n");
> + return -EINVAL;
> + }
> +
> + prd = div;
> + div *= duty_ns;
> + do_div(div, period_ns);
> + dty = div;
> +
> + ret = clk_enable(sunxi_pwm->clk);
> + if (ret) {
> + dev_err(chip->dev, "failed to enable PWM clock\n");
> + return ret;
> + }
> +
> + val = sunxi_pwm_readl(sunxi_pwm, PWM_CTRL_REG);
> +
> + if (sunxi_pwm->data->has_rdy && (val & PWM_RDY(pwm->hwpwm)))
> + return -EBUSY;
clk_disable?
And I'd rather use pm_runtime here.
> + clk_gate = val & BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG, val);
You probably can test clk_gate here to avoid a write if it's already
disabled.
> + val = sunxi_pwm_readl(sunxi_pwm, PWM_CTRL_REG);
> + val &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
> + val |= i;
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG, val);
> +
> + sunxi_pwm_writel(sunxi_pwm, PWM_CH_PRD(pwm->hwpwm), dty | PWM_PRD(prd));
> +
> + val = sunxi_pwm_readl(sunxi_pwm, PWM_CTRL_REG);
> + val |= clk_gate;
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG, val);
And you can test it here too.
> + clk_disable(sunxi_pwm->clk);
> + return ret;
return 0; ?
> +}
> +
> +static int sunxi_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> + enum pwm_polarity polarity)
> +{
> + struct sunxi_pwm_chip *sunxi_pwm = to_sunxi_pwm_chip(chip);
> + u32 val;
> + int ret;
> +
> + val = sunxi_pwm_readl(sunxi_pwm, PWM_CTRL_REG);
> +
> + if (polarity != PWM_POLARITY_NORMAL)
> + val &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
> + else
> + val |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
> +
> + ret = clk_enable(sunxi_pwm->clk);
Hmmm, this should probably be before you access the registers.
> + if (ret) {
> + dev_err(chip->dev, "failed to enable PWM clock\n");
> + return ret;
> + }
> +
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG, val);
> +
> + clk_disable(sunxi_pwm->clk);
> +
> + return 0;
> +}
> +
> +static int sunxi_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct sunxi_pwm_chip *sunxi_pwm = to_sunxi_pwm_chip(chip);
> + u32 val;
> + int ret;
> +
> + ret = clk_enable(sunxi_pwm->clk);
> + if (ret) {
> + dev_err(chip->dev, "failed to enable PWM clock\n");
> + return ret;
> + }
> +
> + val = sunxi_pwm_readl(sunxi_pwm, PWM_CTRL_REG);
> + val |= BIT_CH(PWM_EN, pwm->hwpwm);
> + val |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG, val);
> +
> + return 0;
> +}
> +
> +static void sunxi_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct sunxi_pwm_chip *sunxi_pwm = to_sunxi_pwm_chip(chip);
> + u32 val;
> +
> + val = sunxi_pwm_readl(sunxi_pwm, PWM_CTRL_REG);
> + val &= ~BIT_CH(PWM_EN, pwm->hwpwm);
> + val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG, val);
> +
> + clk_disable(sunxi_pwm->clk);
> +}
> +
> +static const struct pwm_ops sunxi_pwm_ops = {
> + .config = sunxi_pwm_config,
> + .set_polarity = sunxi_pwm_set_polarity,
> + .enable = sunxi_pwm_enable,
> + .disable = sunxi_pwm_disable,
> + .owner = THIS_MODULE,
> +};
> +
> +static const struct sunxi_pwm_data sunxi_pwm_data_v1 = {
> + .has_rdy = false,
> +};
> +
> +static const struct sunxi_pwm_data sunxi_pwm_data_v2 = {
> + .has_rdy = true,
> +};
I'd prefer to see these structures named after the soc they're
associated to.
> +static const struct of_device_id sunxi_pwm_dt_ids[] = {
> + {
> + .compatible = "allwinner,sun4i-pwm",
> + .data = &sunxi_pwm_data_v1,
> + }, {
> + .compatible = "allwinner,sun7i-pwm",
> + .data = &sunxi_pwm_data_v2,
> + }, {
> + /* sentinel */
> + },
> +};
> +MODULE_DEVICE_TABLE(of, sunxi_pwm_dt_ids);
> +
> +static int sunxi_pwm_probe(struct platform_device *pdev)
> +{
> + struct sunxi_pwm_chip *sunxi_pwm;
> + struct resource *res;
> + int ret;
> +
> + const struct of_device_id *match;
> +
> + match = of_match_device(sunxi_pwm_dt_ids, &pdev->dev);
> + if (!match || !match->data)
> + return -ENODEV;
> +
> + sunxi_pwm = devm_kzalloc(&pdev->dev, sizeof(*sunxi_pwm), GFP_KERNEL);
> + if (!sunxi_pwm)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + sunxi_pwm->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(sunxi_pwm->base))
> + return PTR_ERR(sunxi_pwm->base);
> +
> + sunxi_pwm->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(sunxi_pwm->clk))
> + return PTR_ERR(sunxi_pwm->clk);
> +
> + ret = clk_prepare(sunxi_pwm->clk);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to prepare PWM clock\n");
> + return ret;
> + }
> +
> + sunxi_pwm->chip.dev = &pdev->dev;
> + sunxi_pwm->chip.ops = &sunxi_pwm_ops;
> +
> + if (pdev->dev.of_node) {
Which will always happen if of_match_device succeeded.
> + sunxi_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
> + sunxi_pwm->chip.of_pwm_n_cells = 3;
> + }
> +
> + sunxi_pwm->chip.base = -1;
> + sunxi_pwm->chip.npwm = 2;
> + sunxi_pwm->data = match->data;
> +
> + /* By default, the polarity is inversed, set it to normal */
That comment should be after the clk_enable call.
> + ret = clk_enable(sunxi_pwm->clk);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to enable PWM clock\n");
> + goto unprepare_clk;
> + }
> + sunxi_pwm_writel(sunxi_pwm, PWM_CTRL_REG,
> + BIT_CH(PWM_ACT_STATE, 0) |
> + BIT_CH(PWM_ACT_STATE, 1));
> + clk_disable(sunxi_pwm->clk);
> +
> + ret = pwmchip_add(&sunxi_pwm->chip);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret);
> + goto unprepare_clk;
> + }
> +
> + platform_set_drvdata(pdev, sunxi_pwm);
> +
> +
You can drop the extra line.
> + return ret;
> +
> +unprepare_clk:
> + clk_unprepare(sunxi_pwm->clk);
> + return ret;
> +}
> +
> +static int sunxi_pwm_remove(struct platform_device *pdev)
> +{
> + struct sunxi_pwm_chip *sunxi_pwm = platform_get_drvdata(pdev);
> +
> + clk_unprepare(sunxi_pwm->clk);
> +
> + return pwmchip_remove(&sunxi_pwm->chip);
> +}
> +
> +static struct platform_driver sunxi_pwm_driver = {
> + .driver = {
> + .name = "sunxi-pwm",
> + .of_match_table = of_match_ptr(sunxi_pwm_dt_ids),
You can drop the of_match_ptr. CONFIG_OF is always selected, and you
don't protect the definition of sunxi_pwm_dt_ids by an ifdef anyway.
> + },
> + .probe = sunxi_pwm_probe,
> + .remove = sunxi_pwm_remove,
> +};
> +module_platform_driver(sunxi_pwm_driver);
> +
> +MODULE_ALIAS("platform:sunxi-pwm");
> +MODULE_AUTHOR("alexandre Belloni <alexandre.belloni at free-electrons.com>");
> +MODULE_DESCRIPTION("Allwinner PWM driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.8.3.2
>
Thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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