On 19/08/2013 05:11, Bo Shen :
add atmel pwm controller driver based on PWM framework
this is basic function implementation of pwm controller
it can work with pwm based led and backlight
Signed-off-by: Bo Shen <voice.shen@xxxxxxxxx>
---
This patch is based on Linux v3.11 rc6
Tested on sama5d31ek and at91sam9m10g45ek board
---
.../devicetree/bindings/pwm/atmel-pwm.txt | 19 ++
drivers/pwm/Kconfig | 9 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-atmel.c | 327 ++++++++++++++++++++
4 files changed, 356 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..127fcdb
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/atmel-pwm.txt
@@ -0,0 +1,19 @@
+Atmel PWM controller
+
+Required properties:
+ - compatible: should be one of:
+ - "atmel,at91sam9rl-pwm"
+ - "atmel,sama5-pwm"
No, the compatibility string should be: "atmel,sama5d3-pwm"
+ - reg: physical base address and length of the controller's registers
+ - #pwm-cells: Should be 3.
+ - The first cell specifies the per-chip index of the PWM to use
+ - The second cell is the period in nanoseconds
+ - The third cell is used to encode the polarity of PWM output
+
+Example:
+
+ pwm0: pwm@f8034000 {
+ compatible = "atmel,at91sam9rl-pwm";
+ reg = <0xf8034000 0x400>;
+ #pwm-cells = <3>;
+ };
Can you add an example of consumer: it would make the example much more
understandable.
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..b83d68e
--- /dev/null
+++ b/drivers/pwm/pwm-atmel.c
@@ -0,0 +1,327 @@
+/*
+ * Driver for Atmel Pulse Width Modulation Controller
+ *
+ * Copyright (C) 2013 Atmel Semiconductor Technology Ltd.
use "Atmel Corporation" in copyright.
+ * Bo Shen <voice.shen@xxxxxxxxx>
+ *
+ * GPL v2 or later
+ */
A general remark also pointed out by Thierry: please use more defined
constants in your code: it makes the code more readable and avoid this
black magic feeling when we read it.
+#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/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define PWM_MR 0x00
+#define PWM_ENA 0x04
+#define PWM_DIS 0x08
+#define PWM_SR 0x0C
+
+#define PWM_CMR 0x00
+
+/* The following register for PWM v1 */
+#define PWMv1_CDTY 0x04
+#define PWMv1_CPRD 0x08
+#define PWMv1_CUPD 0x10
+
+/* The following register for PWM v2 */
+#define PWMv2_CDTY 0x04
+#define PWMv2_CDTYUPD 0x08
+#define PWMv2_CPRD 0x0C
+#define PWMv2_CPRDUPD 0x10
+
+#define PWM_NUM 4
+
+struct atmel_pwm_chip {
+ struct pwm_chip chip;
+ struct clk *clk;
+ void __iomem *base;
+
+ void (*config)(struct atmel_pwm_chip *chip, struct pwm_device *pwm,
+ unsigned int dty, unsigned int prd);
+};
+
+#define to_atmel_pwm_chip(chip) container_of(chip, struct atmel_pwm_chip, chip)
+
+static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip, int offset)
+{
+ return readl(chip->base + offset);
+}
+
+static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip, int offset,
+ u32 val)
+{
+ writel(val, chip->base + offset);
+}
+
+static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip, int ch,
+ int offset)
+{
+ return readl(chip->base + 0x200 + ch * 0x20 + offset);
Maybe a constant for this 0x200 value...
+}
+
+static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip, int ch,
+ int offset, u32 val)
+{
+ writel(val, chip->base + 0x200 + 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 long val, prd, dty;
+ unsigned long long div, clk_rate;
+ int ret, pres = 0;
+
+ clk_rate = clk_get_rate(atmel_pwm->clk);
+
+ while (1) {
Why not use a proper loop condition here instead of a frightening
while (true) loop? Is it really making the code less readable?
+ div = 1000000000;
use a constant or at least a comment for this initialization.
+ div *= 1 << pres;
+ val = clk_rate * period_ns;
+ prd = div_u64(val, div);
+ val = clk_rate * duty_ns;
+ dty = div_u64(val, div);
+
+ if (prd < 0x0001 || dty < 0x0)
+ return -EINVAL;
+
+ if (prd > 0xffff || dty > 0xffff) {
Yes, here define those constants please.
+ if (++pres > 0x10)
+ return -EINVAL;
+ continue;
+ }
+
+ break;
+ }
+
+ /* Enable clock */
+ ret = clk_prepare_enable(atmel_pwm->clk);
+ if (ret) {
+ pr_err("failed to enable pwm clock\n");
+ return ret;
+ }
+
+ atmel_pwm->config(atmel_pwm, pwm, dty, prd);
+
+ /* Check whether need to disable clock */
+ val = atmel_pwm_readl(atmel_pwm, PWM_SR);
+ if ((val & 0xf) == 0)
Ditto.
+ clk_disable_unprepare(atmel_pwm->clk);
+
+ return 0;
+}
+
+static void atmel_pwm_config_v1(struct atmel_pwm_chip *atmel_pwm,
+ struct pwm_device *pwm, unsigned int dty, unsigned int prd)
+{
+ unsigned int val;
+
+ /*
+ * if the pwm channel is enabled, using update register to update
+ * related register value, or else write it directly
+ */
+ 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 &= ~(1 << 10);
+ 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 atmel_pwm_chip *atmel_pwm,
+ struct pwm_device *pwm, unsigned int dty, unsigned int prd)
+{
+ /*
+ * if the pwm channel is enabled, using update register to update
+ * related register value, or else write it directly
+ */
+ if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+ atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMv2_CDTYUPD, dty);
+ atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMv2_CPRDUPD, prd);
+ } 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;
+
+ /* Enable clock */
+ ret = clk_prepare_enable(atmel_pwm->clk);
+ if (ret) {
+ pr_err("failed to enable pwm clock\n");
+ return ret;
+ }
+
+ if (polarity == PWM_POLARITY_NORMAL)
+ val &= ~(1 << 9);
+ else
+ val |= 1 << 9;
Ditto.
+
+ atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
+
+ /* Disable clock */
+ clk_disable_unprepare(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);
+
+ /* Disable clock */
+ val = atmel_pwm_readl(atmel_pwm, PWM_SR);
+ if ((val & 0xf) == 0)
+ clk_disable_unprepare(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 atmel_pwm_chip *chip, struct pwm_device *pwm,
+ unsigned int dty, unsigned int prd);
+};
+
+static struct atmel_pwm_data atmel_pwm_data_v1 = {
+ .config = atmel_pwm_config_v1,
+};
+
+static struct atmel_pwm_data atmel_pwm_data_v2 = {
+ .config = atmel_pwm_config_v2,
+};
+
+static const struct of_device_id atmel_pwm_dt_ids[] = {
+ {
+ .compatible = "atmel,at91sam9rl-pwm",
+ .data = &atmel_pwm_data_v1,
+ }, {
+ .compatible = "atmel,sama5-pwm",
+ .data = &atmel_pwm_data_v2,
+ }, {
+ /* sentinel */
+ },
+};
+MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
+
+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;
+ struct pinctrl *pinctrl;
+ int ret;
+
+ pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
+ if (IS_ERR(pinctrl)) {
+ dev_err(&pdev->dev, "failed get pinctrl\n");
+ return PTR_ERR(pinctrl);
+ }
As said by Thierry: already done in core driver code.
+
+ atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL);
+ if (!atmel_pwm) {
+ dev_err(&pdev->dev, "out of memory\n");
+ return -ENOMEM;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "no memory resource defined\n");
+ return -ENODEV;
+ }
+
+ atmel_pwm->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(atmel_pwm->base)) {
+ dev_err(&pdev->dev, "ioremap failed\n");
+ return PTR_ERR(atmel_pwm->base);
+ }
+
+ atmel_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
+ if (IS_ERR(atmel_pwm->clk)) {
+ dev_err(&pdev->dev, "clk get failed\n");
+ return PTR_ERR(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 = PWM_NUM;
+
+ 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);
+
+ dev_info(&pdev->dev, "successfully register pwm\n");
+
+ return 0;
+}
+
+static int atmel_pwm_remove(struct platform_device *pdev)
+{
+ struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);
+
+ 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");
--
Nicolas Ferre
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