[PATCH v6 1/2] PWM: atmel-pwm: add PWM controller driver

[Bo Shen]

Add Atmel PWM controller driver based on PWM framework.

This is the basic function implementation of Atmel PWM controller.
It can work with PWM based led and backlight.

Signed-off-by: Bo Shen <voice.shen@xxxxxxxxx>

---
Changes in v6:
  - using relaxed version for writel and readl
  - add none device tree support
  - change some define from lower case to upper case
  - split device tree binding document as a separate patch

Changes in v5:
  - call clk_disable directly, if so, it won't cause more than one channel
    enabled, the clock can not be disabled.

Changes in v4:
  - check the return value of clk_prepare()
  - change channel register size as constant

Changes in v3:
  - change compatible string from "atmel,sama5-pwm" to "atmel,sama5d3-pwm"
  - Add PWM led example in binding documentation
  - Using micro replace hard code

Changes in v2:
  - Address the comments from Thierry Reding

 drivers/pwm/Kconfig     |    9 ++
 drivers/pwm/Makefile    |    1 +
 drivers/pwm/pwm-atmel.c |  360 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 370 insertions(+)
 create mode 100644 drivers/pwm/pwm-atmel.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 75840b5..54237b9 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -41,6 +41,15 @@ config PWM_AB8500
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-ab8500.
 
+config PWM_ATMEL
+	tristate "Atmel PWM support"
+	depends on ARCH_AT91
+	help
+	  Generic PWM framework driver for Atmel SoC.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-atmel.
+
 config PWM_ATMEL_TCB
 	tristate "Atmel TC Block PWM support"
 	depends on ATMEL_TCLIB && OF
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 77a8c18..5b193f8 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -1,6 +1,7 @@
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_SYSFS)		+= sysfs.o
 obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
+obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
 obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
new file mode 100644
index 0000000..ac54252
--- /dev/null
+++ b/drivers/pwm/pwm-atmel.c
@@ -0,0 +1,360 @@
+/*
+ * Driver for Atmel Pulse Width Modulation Controller
+ *
+ * Copyright (C) 2013 Atmel Corporation
+ *		 Bo Shen <voice.shen@xxxxxxxxx>
+ *
+ * Licensed under GPLv2.
+ */
+
+#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>
+
+/* The following is global registers for PWM controller */
+#define PWM_ENA			0x04
+#define PWM_DIS			0x08
+#define PWM_SR			0x0C
+/* bit field in SR */
+#define PWM_SR_ALL_CH_ON	0x0F
+
+/* The following register is PWM channel related registers */
+#define PWM_CH_REG_OFFSET	0x200
+#define PWM_CH_REG_SIZE		0x20
+
+#define PWM_CMR			0x0
+/* bit field in CMR */
+#define PWM_CMR_CPOL		(1 << 9)
+#define PWM_CMR_UPD_CDTY	(1 << 10)
+
+/* The following registers for PWM v1 */
+#define PWMV1_CDTY		0x04
+#define PWMV1_CPRD		0x08
+#define PWMV1_CUPD		0x10
+
+/* The following registers for PWM v2 */
+#define PWMV2_CDTY		0x04
+#define PWMV2_CDTYUPD		0x08
+#define PWMV2_CPRD		0x0C
+#define PWMV2_CPRDUPD		0x10
+
+/* max value for duty and period */
+/*
+ * Although the duty and period register is 32 bit,
+ * however only the LSB 16 bits are significant.
+ */
+#define PWM_MAX_DTY		0xFFFF
+#define PWM_MAX_PRD		0xFFFF
+#define PRD_MAX_PRES		10
+
+struct atmel_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	void __iomem *base;
+
+	void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
+		       int dty, int prd);
+};
+
+static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct atmel_pwm_chip, chip);
+}
+
+static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip,
+				  unsigned long offset)
+{
+	return readl_relaxed(chip->base + offset);
+}
+
+static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
+				    unsigned long offset, unsigned long val)
+{
+	writel_relaxed(val, chip->base + offset);
+}
+
+static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
+				     unsigned int ch, unsigned long offset)
+{
+	return readl_relaxed(chip->base + PWM_CH_REG_OFFSET +
+			ch * PWM_CH_REG_SIZE + offset);
+}
+
+static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
+				       unsigned int ch, unsigned long offset,
+				       unsigned long val)
+{
+	writel_relaxed(val, chip->base + PWM_CH_REG_OFFSET +
+			ch * PWM_CH_REG_SIZE + offset);
+}
+
+static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+		int duty_ns, int period_ns)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	unsigned long clk_rate, prd, dty;
+	unsigned long long div;
+	int ret, pres = 0;
+
+	clk_rate = clk_get_rate(atmel_pwm->clk);
+	div = clk_rate;
+
+	/* Calculate the period cycles */
+	while (div > PWM_MAX_PRD) {
+		div = clk_rate / (1 << pres);
+		div = div * period_ns;
+		/* 1/Hz = 100000000 ns */
+		do_div(div, 1000000000);
+
+		if (pres++ > PRD_MAX_PRES) {
+			pr_err("PRES is bigger than maximum pre-scaler\n");
+			return -EINVAL;
+		}
+	}
+
+	/* Calculate the duty cycles */
+	prd = div;
+	div *= duty_ns;
+	do_div(div, period_ns);
+	dty = div;
+
+	ret = clk_enable(atmel_pwm->clk);
+	if (ret) {
+		pr_err("Failed to enable pwm clock\n");
+		return ret;
+	}
+
+	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, pres);
+	atmel_pwm->config(chip, pwm, dty, prd);
+
+	clk_disable(atmel_pwm->clk);
+
+	return 0;
+}
+
+static void atmel_pwm_config_v1(struct pwm_chip *chip, struct pwm_device *pwm,
+				int dty, int prd)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	unsigned int val;
+
+	/*
+	 * If the PWM channel is disabled, write value to duty and period
+	 * registers directly.
+	 * If the PWM channel is enabled, using the update register, it needs
+	 * to set bit 10 of CMR to 0
+	 */
+	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CUPD, dty);
+
+		val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
+		val &= ~PWM_CMR_UPD_CDTY;
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
+	} else {
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CDTY, dty);
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CPRD, prd);
+	}
+}
+
+static void atmel_pwm_config_v2(struct pwm_chip *chip, struct pwm_device *pwm,
+				int dty, int prd)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+
+	/*
+	 * If the PWM channel is disabled, write value to duty and period
+	 * registers directly.
+	 * If the PWM channel is enabled, using the duty update register to
+	 * update the value.
+	 */
+	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTYUPD, dty);
+	} else {
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTY, dty);
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CPRD, prd);
+	}
+}
+
+static int atmel_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+		enum pwm_polarity polarity)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	u32 val = 0;
+	int ret;
+
+	if (polarity == PWM_POLARITY_NORMAL)
+		val &= ~PWM_CMR_CPOL;
+	else
+		val |= PWM_CMR_CPOL;
+
+	ret = clk_enable(atmel_pwm->clk);
+	if (ret) {
+		pr_err("failed to enable pwm clock\n");
+		return ret;
+	}
+
+	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
+
+	clk_disable(atmel_pwm->clk);
+
+	return 0;
+}
+
+static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	int ret;
+
+	ret = clk_enable(atmel_pwm->clk);
+	if (ret) {
+		pr_err("failed to enable pwm clock\n");
+		return ret;
+	}
+
+	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
+
+	return 0;
+}
+
+static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+
+	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
+
+	clk_disable(atmel_pwm->clk);
+}
+
+static const struct pwm_ops atmel_pwm_ops = {
+	.config = atmel_pwm_config,
+	.set_polarity = atmel_pwm_set_polarity,
+	.enable = atmel_pwm_enable,
+	.disable = atmel_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+struct atmel_pwm_data {
+	void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
+		       int dty, int prd);
+};
+
+static const struct atmel_pwm_data atmel_pwm_data_v1 = {
+	.config = atmel_pwm_config_v1,
+};
+
+static const struct atmel_pwm_data atmel_pwm_data_v2 = {
+	.config = atmel_pwm_config_v2,
+};
+
+static const struct platform_device_id atmel_pwm_devtypes[] = {
+	{
+		.name = "at91sam9rl-pwm",
+		.driver_data = (kernel_ulong_t)&atmel_pwm_data_v1,
+	}, {
+		.name = "sama5d3-pwm",
+		.driver_data = (kernel_ulong_t)&atmel_pwm_data_v2,
+	}, {
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(platform, atmel_pwm_devtypes);
+
+#ifdef CONFIG_OF
+static const struct of_device_id atmel_pwm_dt_ids[] = {
+	{
+		.compatible = "atmel,at91sam9rl-pwm",
+		.data = &atmel_pwm_data_v1,
+	}, {
+		.compatible = "atmel,sama5d3-pwm",
+		.data = &atmel_pwm_data_v2,
+	}, {
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
+#endif
+
+static int atmel_pwm_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *of_id =
+		of_match_device(atmel_pwm_dt_ids, &pdev->dev);
+	const struct atmel_pwm_data *data;
+	struct atmel_pwm_chip *atmel_pwm;
+	struct resource *res;
+	int ret;
+
+	atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL);
+	if (!atmel_pwm)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	atmel_pwm->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(atmel_pwm->base))
+		return PTR_ERR(atmel_pwm->base);
+
+	atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(atmel_pwm->clk))
+		return PTR_ERR(atmel_pwm->clk);
+
+	ret = clk_prepare(atmel_pwm->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to prepare pwm clock\n");
+		return ret;
+	}
+
+	atmel_pwm->chip.dev = &pdev->dev;
+	atmel_pwm->chip.ops = &atmel_pwm_ops;
+	atmel_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
+	atmel_pwm->chip.of_pwm_n_cells = 3;
+	atmel_pwm->chip.base = -1;
+	atmel_pwm->chip.npwm = 4;
+
+	data = of_id->data;
+	atmel_pwm->config = data->config;
+
+	ret = pwmchip_add(&atmel_pwm->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
+		goto unprepare_clk;
+	}
+
+	platform_set_drvdata(pdev, atmel_pwm);
+
+unprepare_clk:
+	clk_unprepare(atmel_pwm->clk);
+	return ret;
+}
+
+static int atmel_pwm_remove(struct platform_device *pdev)
+{
+	struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);
+
+	clk_unprepare(atmel_pwm->clk);
+
+	return pwmchip_remove(&atmel_pwm->chip);
+}
+
+static struct platform_driver atmel_pwm_driver = {
+	.driver = {
+		.name = "atmel-pwm",
+		.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
+	},
+	.id_table = atmel_pwm_devtypes,
+	.probe = atmel_pwm_probe,
+	.remove = atmel_pwm_remove,
+};
+module_platform_driver(atmel_pwm_driver);
+
+MODULE_ALIAS("platform:atmel-pwm");
+MODULE_AUTHOR("Bo Shen <voice.shen@xxxxxxxxx>");
+MODULE_DESCRIPTION("Atmel PWM driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

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