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Message-ID: <54442BB1.1080403@mleia.com>
Date: Mon, 20 Oct 2014 00:22:57 +0300
From: Vladimir Zapolskiy <vz@...ia.com>
To: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC: Thierry Reding <thierry.reding@...il.com>,
Maxime Ripard <maxime.ripard@...e-electrons.com>,
jonsmirl@...il.com, Simon <longsleep@...il.com>,
linux-pwm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCHv8 1/2] pwm: Add Allwinner SoC support
Hello Alexandre,
On 19.10.2014 21:28, 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@...e-electrons.com>
> Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> ---
> drivers/pwm/Kconfig | 9 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-sun4i.c | 371 ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 381 insertions(+)
> create mode 100644 drivers/pwm/pwm-sun4i.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 3865dfb9ed08..424359d3cbb1 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -262,6 +262,15 @@ config PWM_STI
> To compile this driver as a module, choose M here: the module
> will be called pwm-sti.
>
> +config PWM_SUN4I
> + tristate "Allwinner sun4i PWM support"
> + depends on ARCH_SUNXI || COMPILE_TEST
> + help
> + Generic PWM framework driver for Allwinner sun4i and sun7i SoCs.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called pwm-sun4i.
> +
> config PWM_TEGRA
> tristate "NVIDIA Tegra PWM support"
> depends on ARCH_TEGRA
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index c458606c3755..d607804deea1 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o
> obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
> obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o
> obj-$(CONFIG_PWM_STI) += pwm-sti.o
> +obj-$(CONFIG_PWM_SUN4I) += pwm-sun4i.o
> obj-$(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-sun4i.c b/drivers/pwm/pwm-sun4i.c
> new file mode 100644
> index 000000000000..918f8ee79b51
> --- /dev/null
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -0,0 +1,371 @@
> +/*
> + * Driver for Allwinner sun4i Pulse Width Modulation Controller
> + *
> + * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@...e-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/mutex.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/time.h>
> +
> +#define PWM_CTRL_REG 0x0
> +
> +#define PWM_CH_PRD_BASE 0x4
> +#define PWM_CH_PRD_OFFSET 0x4
> +#define PWM_CH_PRD(ch) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch))
> +
> +#define PWMCH_OFFSET 15
> +#define PWM_PRESCAL_MASK GENMASK(3, 0)
> +#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_OFFSET 1
> +#define PWM_RDY(ch) BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch))
> +
> +#define PWM_PRD(prd) (((prd) - 1) << 16)
> +#define PWM_PRD_MASK GENMASK(15, 0)
> +
> +#define PWM_DTY_MASK GENMASK(15, 0)
> +
> +#define BIT_CH(bit, chan) ((bit) << ((chan) * PWMCH_OFFSET))
> +
> +static const u32 prescaler_table[] = {
> + 120,
> + 180,
> + 240,
> + 360,
> + 480,
> + 0,
> + 0,
> + 0,
> + 12000,
> + 24000,
> + 36000,
> + 48000,
> + 72000,
> + 0,
> + 0,
> + 0, /* Actually 1 but tested separately */
> +};
> +
> +struct sun4i_pwm_data {
> + bool has_prescaler_bypass;
> + bool has_rdy;
> +};
> +
> +struct sun4i_pwm_chip {
> + struct pwm_chip chip;
> + struct clk *clk;
> + void __iomem *base;
> + struct mutex ctrl_lock;
why do you use mutex? I haven't found any blocking subcalls under
protection, a spinlock seems to fit better here.
Vladimir
> + const struct sun4i_pwm_data *data;
> +};
> +
> +static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
> +{
> + return container_of(chip, struct sun4i_pwm_chip, chip);
> +}
> +
> +static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
> + unsigned long offset)
> +{
> + return readl(chip->base + offset);
> +}
> +
> +static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
> + u32 val, unsigned long offset)
> +{
> + writel(val, chip->base + offset);
> +}
> +
> +static int sun4i_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> + int duty_ns, int period_ns)
> +{
> + struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
> + u32 clk_rate, prd, dty, val, clk_gate;
> + u64 div = 0;
> + unsigned int prescaler = 0;
> + int err;
> +
> + clk_rate = clk_get_rate(sun4i_pwm->clk);
> +
> + if (sun4i_pwm->data->has_prescaler_bypass) {
> + /* First, test without any prescaler when available */
> + prescaler = PWM_PRESCAL_MASK;
> + /*
> + * When not using any prescaler, the clock period in nanoseconds
> + * is not an integer so round it half up instead of
> + * truncating to get less surprising values.
> + */
> + div = clk_rate * (u64)period_ns + NSEC_PER_SEC/2;
> + do_div(div, NSEC_PER_SEC);
> + if (div - 1 > PWM_PRD_MASK)
> + prescaler = 0;
> + }
> +
> + if (prescaler == 0) {
> + /* Go up from the first divider */
> + for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) {
> + if (!prescaler_table[prescaler])
> + continue;
> + div = clk_rate / prescaler_table[prescaler];
> + div = div * (u64)period_ns;
> + do_div(div, NSEC_PER_SEC);
> + if (div - 1 <= PWM_PRD_MASK)
> + break;
> + }
> +
> + if (div - 1 > PWM_PRD_MASK) {
> + dev_err(chip->dev, "period exceeds the maximum value\n");
> + return -EINVAL;
> + }
> + }
> +
> + prd = div;
> + div *= duty_ns;
> + do_div(div, period_ns);
> + dty = div;
> +
> + err = clk_prepare_enable(sun4i_pwm->clk);
> + if (err) {
> + dev_err(chip->dev, "failed to enable PWM clock\n");
> + return err;
> + }
> +
> + mutex_lock(&sun4i_pwm->ctrl_lock);
> + val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
> +
> + if (sun4i_pwm->data->has_rdy && (val & PWM_RDY(pwm->hwpwm))) {
> + mutex_unlock(&sun4i_pwm->ctrl_lock);
> + clk_disable_unprepare(sun4i_pwm->clk);
> + return -EBUSY;
> + }
> +
> + clk_gate = val & BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + if (clk_gate) {
> + val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
> + }
> +
> + val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
> + val &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
> + val |= BIT_CH(prescaler, pwm->hwpwm);
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
> +
> + val = (dty & PWM_DTY_MASK) | PWM_PRD(prd);
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
> +
> + if (clk_gate) {
> + val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
> + val |= clk_gate;
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
> + }
> +
> + mutex_unlock(&sun4i_pwm->ctrl_lock);
> + clk_disable_unprepare(sun4i_pwm->clk);
> +
> + return 0;
> +}
> +
> +static int sun4i_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> + enum pwm_polarity polarity)
> +{
> + struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
> + u32 val;
> + int ret;
> +
> + ret = clk_prepare_enable(sun4i_pwm->clk);
> + if (ret) {
> + dev_err(chip->dev, "failed to enable PWM clock\n");
> + return ret;
> + }
> +
> + mutex_lock(&sun4i_pwm->ctrl_lock);
> + val = sun4i_pwm_readl(sun4i_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);
> +
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
> +
> + mutex_unlock(&sun4i_pwm->ctrl_lock);
> + clk_disable_unprepare(sun4i_pwm->clk);
> +
> + return 0;
> +}
> +
> +static int sun4i_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
> + u32 val;
> + int ret;
> +
> + ret = clk_prepare_enable(sun4i_pwm->clk);
> + if (ret) {
> + dev_err(chip->dev, "failed to enable PWM clock\n");
> + return ret;
> + }
> +
> + mutex_lock(&sun4i_pwm->ctrl_lock);
> + val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
> + val |= BIT_CH(PWM_EN, pwm->hwpwm);
> + val |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
> + mutex_unlock(&sun4i_pwm->ctrl_lock);
> +
> + return 0;
> +}
> +
> +static void sun4i_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
> + u32 val;
> +
> + mutex_lock(&sun4i_pwm->ctrl_lock);
> + val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
> + val &= ~BIT_CH(PWM_EN, pwm->hwpwm);
> + val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
> + sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
> + mutex_unlock(&sun4i_pwm->ctrl_lock);
> +
> + clk_disable_unprepare(sun4i_pwm->clk);
> +}
> +
> +static const struct pwm_ops sun4i_pwm_ops = {
> + .config = sun4i_pwm_config,
> + .set_polarity = sun4i_pwm_set_polarity,
> + .enable = sun4i_pwm_enable,
> + .disable = sun4i_pwm_disable,
> + .owner = THIS_MODULE,
> +};
> +
> +static const struct sun4i_pwm_data sun4i_pwm_data_a10 = {
> + .has_prescaler_bypass = false,
> + .has_rdy = false,
> +};
> +
> +static const struct sun4i_pwm_data sun4i_pwm_data_a20 = {
> + .has_prescaler_bypass = true,
> + .has_rdy = true,
> +};
> +
> +static const struct of_device_id sun4i_pwm_dt_ids[] = {
> + {
> + .compatible = "allwinner,sun4i-a10-pwm",
> + .data = &sun4i_pwm_data_a10,
> + }, {
> + .compatible = "allwinner,sun7i-a20-pwm",
> + .data = &sun4i_pwm_data_a20,
> + }, {
> + /* sentinel */
> + },
> +};
> +MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids);
> +
> +static int sun4i_pwm_probe(struct platform_device *pdev)
> +{
> + struct sun4i_pwm_chip *pwm;
> + struct resource *res;
> + u32 val;
> + int i, ret;
> + const struct of_device_id *match;
> +
> + match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
> +
> + 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->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(pwm->clk))
> + return PTR_ERR(pwm->clk);
> +
> + pwm->chip.dev = &pdev->dev;
> + pwm->chip.ops = &sun4i_pwm_ops;
> + pwm->chip.base = -1;
> + pwm->chip.npwm = 2;
> + pwm->chip.can_sleep = true;
> + pwm->chip.of_xlate = of_pwm_xlate_with_flags;
> + pwm->chip.of_pwm_n_cells = 3;
> + pwm->data = match->data;
> +
> + mutex_init(&pwm->ctrl_lock);
> +
> + ret = pwmchip_add(&pwm->chip);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
> + goto error;
> + }
> +
> + platform_set_drvdata(pdev, pwm);
> +
> + ret = clk_prepare_enable(pwm->clk);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to enable PWM clock\n");
> + goto clk_error;
> + }
> +
> + val = sun4i_pwm_readl(pwm, PWM_CTRL_REG);
> + for (i = 0; i < pwm->chip.npwm; i++) {
> + if (!(val & BIT_CH(PWM_ACT_STATE, i)))
> + pwm->chip.pwms[i].polarity = PWM_POLARITY_INVERSED;
> + }
> + clk_disable_unprepare(pwm->clk);
> +
> + return 0;
> +
> +clk_error:
> + pwmchip_remove(&pwm->chip);
> +
> +error:
> + mutex_destroy(&pwm->ctrl_lock);
> + return ret;
> +}
> +
> +static int sun4i_pwm_remove(struct platform_device *pdev)
> +{
> + struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
> +
> + mutex_destroy(&pwm->ctrl_lock);
> +
> + return pwmchip_remove(&pwm->chip);
> +}
> +
> +static struct platform_driver sun4i_pwm_driver = {
> + .driver = {
> + .name = "sun4i-pwm",
> + .of_match_table = sun4i_pwm_dt_ids,
> + },
> + .probe = sun4i_pwm_probe,
> + .remove = sun4i_pwm_remove,
> +};
> +module_platform_driver(sun4i_pwm_driver);
> +
> +MODULE_ALIAS("platform:sun4i-pwm");
> +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@...e-electrons.com>");
> +MODULE_DESCRIPTION("Allwinner sun4i PWM driver");
> +MODULE_LICENSE("GPL v2");
>
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