[PATCH v3] PWM: at91: add Atmel PWM controller driver
From: Bo Shen
Date: Sun Sep 22 2013 - 04:06:44 EST
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 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
.../devicetree/bindings/pwm/atmel-pwm.txt | 41 +++
drivers/pwm/Kconfig | 9 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-atmel.c | 335 ++++++++++++++++++++
4 files changed, 386 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/atmel-pwm.txt
create mode 100644 drivers/pwm/pwm-atmel.c
diff --git a/Documentation/devicetree/bindings/pwm/atmel-pwm.txt b/Documentation/devicetree/bindings/pwm/atmel-pwm.txt
new file mode 100644
index 0000000..1c1a5fa
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/atmel-pwm.txt
@@ -0,0 +1,41 @@
+Atmel PWM controller
+
+Required properties:
+ - compatible: should be one of:
+ - "atmel,at91sam9rl-pwm"
+ - "atmel,sama5d3-pwm"
+ - reg: physical base address and length of the controller's registers
+ - #pwm-cells: Should be 3. See pwm.txt in this directory for a
+ description of the cells format
+
+Example:
+
+ pwm0: pwm@f8034000 {
+ compatible = "atmel,at91sam9rl-pwm";
+ reg = <0xf8034000 0x400>;
+ #pwm-cells = <3>;
+ };
+
+The following the pwm led based example:
+
+ pwm0: pwm@f8034000 {
+ compatible = "atmel,at91sam9rl-pwm";
+ reg = <0xf8034000 0x400>;
+ #pwm-cells = <3>;
+ };
+
+ pwdleds {
+ compatible = "pwm-leds";
+
+ d1 {
+ label = "d1";
+ pwms = <&pwm0 3 5000 0>
+ max-brightness = <255>;
+ };
+
+ d2 {
+ label = "d2";
+ pwms = <&pwm0 1 5000 1>
+ max-brightness = <255>;
+ };
+ };
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..9c86dfe
--- /dev/null
+++ b/drivers/pwm/pwm-atmel.c
@@ -0,0 +1,335 @@
+/*
+ * 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_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(chip->base + offset);
+}
+
+static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
+ unsigned long offset, unsigned long val)
+{
+ writel(val, chip->base + offset);
+}
+
+static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
+ unsigned int ch, unsigned long offset)
+{
+ return readl(chip->base + PWM_CH_REG_OFFSET + ch * 0x20 + offset);
+}
+
+static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
+ unsigned int ch, unsigned long offset,
+ unsigned long val)
+{
+ writel(val, chip->base + PWM_CH_REG_OFFSET + ch * 0x20 + 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 val, 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);
+
+ /* Check whether need to disable clock */
+ val = atmel_pwm_readl(atmel_pwm, PWM_SR);
+ if ((val & PWM_SR_ALL_CH_ON) == 0)
+ 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;
+
+ ret = clk_enable(atmel_pwm->clk);
+ if (ret) {
+ pr_err("failed to enable pwm clock\n");
+ return ret;
+ }
+
+ if (polarity == PWM_POLARITY_NORMAL)
+ val &= ~PWM_CMR_CPOL;
+ else
+ val |= PWM_CMR_CPOL;
+
+ 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);
+
+ clk_prepare_enable(atmel_pwm->clk);
+
+ 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);
+ u32 val;
+
+ atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
+
+ val = atmel_pwm_readl(atmel_pwm, PWM_SR);
+ if ((val & PWM_SR_ALL_CH_ON) == 0)
+ 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,
+};
+
+#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);
+
+ atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(atmel_pwm->clk))
+ return PTR_ERR(atmel_pwm->clk);
+ clk_prepare(atmel_pwm->clk);
+
+ 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);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, atmel_pwm);
+
+ return 0;
+}
+
+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),
+ },
+ .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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