ARM: 5628/1: ep93xx: Introduce Pulse Width Modulator (PWM) driver
The EP93xx features two PWMs (one on the EP9307) with the following
features:
* Configurable dual output
* Separate input clocks for each PWM output
* 16-bit resolution
* Programmable pulse width (duty cycle), interval (frequency), and
polarity
This adds the necessary core support as well as the driver. A sysfs
interface is provided to control the PWM outputs.
Signed-off-by: Matthieu Crapet <mcrapet@gmail.com>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 68ab39d..df1f86b 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -233,6 +233,19 @@
This driver can also be built as a module. If so, the module
will be called isl29003.
+config EP93XX_PWM
+ tristate "EP93xx PWM support"
+ depends on ARCH_EP93XX
+ help
+ This option enables device driver support for the PWM channels
+ on the Cirrus EP93xx processors. The EP9307 chip only has one
+ PWM channel all the others have two, the second channel is an
+ alternate function of the EGPIO14 pin. A sysfs interface is
+ provided to control the PWM channels.
+
+ To compile this driver as a module, choose M here: the module will
+ be called ep93xx_pwm.
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 36f733c..f982d2e 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -19,6 +19,7 @@
obj-$(CONFIG_SGI_GRU) += sgi-gru/
obj-$(CONFIG_HP_ILO) += hpilo.o
obj-$(CONFIG_ISL29003) += isl29003.o
+obj-$(CONFIG_EP93XX_PWM) += ep93xx_pwm.o
obj-$(CONFIG_C2PORT) += c2port/
obj-y += eeprom/
obj-y += cb710/
diff --git a/drivers/misc/ep93xx_pwm.c b/drivers/misc/ep93xx_pwm.c
new file mode 100644
index 0000000..ba46941
--- /dev/null
+++ b/drivers/misc/ep93xx_pwm.c
@@ -0,0 +1,384 @@
+/*
+ * Simple PWM driver for EP93XX
+ *
+ * (c) Copyright 2009 Matthieu Crapet <mcrapet@gmail.com>
+ * (c) Copyright 2009 H Hartley Sweeten <hsweeten@visionengravers.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * EP9307 has only one channel:
+ * - PWMOUT
+ *
+ * EP9301/02/12/15 have two channels:
+ * - PWMOUT
+ * - PWMOUT1 (alternate function for EGPIO14)
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+
+#include <mach/platform.h>
+
+#define EP93XX_PWMx_TERM_COUNT 0x00
+#define EP93XX_PWMx_DUTY_CYCLE 0x04
+#define EP93XX_PWMx_ENABLE 0x08
+#define EP93XX_PWMx_INVERT 0x0C
+
+#define EP93XX_PWM_MAX_COUNT 0xFFFF
+
+struct ep93xx_pwm {
+ void __iomem *mmio_base;
+ struct clk *clk;
+ u32 duty_percent;
+};
+
+static inline void ep93xx_pwm_writel(struct ep93xx_pwm *pwm,
+ unsigned int val, unsigned int off)
+{
+ __raw_writel(val, pwm->mmio_base + off);
+}
+
+static inline unsigned int ep93xx_pwm_readl(struct ep93xx_pwm *pwm,
+ unsigned int off)
+{
+ return __raw_readl(pwm->mmio_base + off);
+}
+
+static inline void ep93xx_pwm_write_tc(struct ep93xx_pwm *pwm, u16 value)
+{
+ ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_TERM_COUNT);
+}
+
+static inline u16 ep93xx_pwm_read_tc(struct ep93xx_pwm *pwm)
+{
+ return ep93xx_pwm_readl(pwm, EP93XX_PWMx_TERM_COUNT);
+}
+
+static inline void ep93xx_pwm_write_dc(struct ep93xx_pwm *pwm, u16 value)
+{
+ ep93xx_pwm_writel(pwm, value, EP93XX_PWMx_DUTY_CYCLE);
+}
+
+static inline void ep93xx_pwm_enable(struct ep93xx_pwm *pwm)
+{
+ ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_ENABLE);
+}
+
+static inline void ep93xx_pwm_disable(struct ep93xx_pwm *pwm)
+{
+ ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_ENABLE);
+}
+
+static inline int ep93xx_pwm_is_enabled(struct ep93xx_pwm *pwm)
+{
+ return ep93xx_pwm_readl(pwm, EP93XX_PWMx_ENABLE) & 0x1;
+}
+
+static inline void ep93xx_pwm_invert(struct ep93xx_pwm *pwm)
+{
+ ep93xx_pwm_writel(pwm, 0x1, EP93XX_PWMx_INVERT);
+}
+
+static inline void ep93xx_pwm_normal(struct ep93xx_pwm *pwm)
+{
+ ep93xx_pwm_writel(pwm, 0x0, EP93XX_PWMx_INVERT);
+}
+
+static inline int ep93xx_pwm_is_inverted(struct ep93xx_pwm *pwm)
+{
+ return ep93xx_pwm_readl(pwm, EP93XX_PWMx_INVERT) & 0x1;
+}
+
+/*
+ * /sys/devices/platform/ep93xx-pwm.N
+ * /min_freq read-only minimum pwm output frequency
+ * /max_req read-only maximum pwm output frequency
+ * /freq read-write pwm output frequency (0 = disable output)
+ * /duty_percent read-write pwm duty cycle percent (1..99)
+ * /invert read-write invert pwm output
+ */
+
+static ssize_t ep93xx_pwm_get_min_freq(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+ unsigned long rate = clk_get_rate(pwm->clk);
+
+ return sprintf(buf, "%ld\n", rate / (EP93XX_PWM_MAX_COUNT + 1));
+}
+
+static ssize_t ep93xx_pwm_get_max_freq(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+ unsigned long rate = clk_get_rate(pwm->clk);
+
+ return sprintf(buf, "%ld\n", rate / 2);
+}
+
+static ssize_t ep93xx_pwm_get_freq(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+
+ if (ep93xx_pwm_is_enabled(pwm)) {
+ unsigned long rate = clk_get_rate(pwm->clk);
+ u16 term = ep93xx_pwm_read_tc(pwm);
+
+ return sprintf(buf, "%ld\n", rate / (term + 1));
+ } else {
+ return sprintf(buf, "disabled\n");
+ }
+}
+
+static ssize_t ep93xx_pwm_set_freq(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+ long val;
+ int err;
+
+ err = strict_strtol(buf, 10, &val);
+ if (err)
+ return -EINVAL;
+
+ if (val == 0) {
+ ep93xx_pwm_disable(pwm);
+ } else if (val <= (clk_get_rate(pwm->clk) / 2)) {
+ u32 term, duty;
+
+ val = (clk_get_rate(pwm->clk) / val) - 1;
+ if (val > EP93XX_PWM_MAX_COUNT)
+ val = EP93XX_PWM_MAX_COUNT;
+ if (val < 1)
+ val = 1;
+
+ term = ep93xx_pwm_read_tc(pwm);
+ duty = ((val + 1) * pwm->duty_percent / 100) - 1;
+
+ /* If pwm is running, order is important */
+ if (val > term) {
+ ep93xx_pwm_write_tc(pwm, val);
+ ep93xx_pwm_write_dc(pwm, duty);
+ } else {
+ ep93xx_pwm_write_dc(pwm, duty);
+ ep93xx_pwm_write_tc(pwm, val);
+ }
+
+ if (!ep93xx_pwm_is_enabled(pwm))
+ ep93xx_pwm_enable(pwm);
+ } else {
+ return -EINVAL;
+ }
+
+ return count;
+}
+
+static ssize_t ep93xx_pwm_get_duty_percent(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+
+ return sprintf(buf, "%d\n", pwm->duty_percent);
+}
+
+static ssize_t ep93xx_pwm_set_duty_percent(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+ long val;
+ int err;
+
+ err = strict_strtol(buf, 10, &val);
+ if (err)
+ return -EINVAL;
+
+ if (val > 0 && val < 100) {
+ u32 term = ep93xx_pwm_read_tc(pwm);
+ ep93xx_pwm_write_dc(pwm, ((term + 1) * val / 100) - 1);
+ pwm->duty_percent = val;
+ return count;
+ }
+
+ return -EINVAL;
+}
+
+static ssize_t ep93xx_pwm_get_invert(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+
+ return sprintf(buf, "%d\n", ep93xx_pwm_is_inverted(pwm));
+}
+
+static ssize_t ep93xx_pwm_set_invert(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+ long val;
+ int err;
+
+ err = strict_strtol(buf, 10, &val);
+ if (err)
+ return -EINVAL;
+
+ if (val == 0)
+ ep93xx_pwm_normal(pwm);
+ else if (val == 1)
+ ep93xx_pwm_invert(pwm);
+ else
+ return -EINVAL;
+
+ return count;
+}
+
+static DEVICE_ATTR(min_freq, S_IRUGO, ep93xx_pwm_get_min_freq, NULL);
+static DEVICE_ATTR(max_freq, S_IRUGO, ep93xx_pwm_get_max_freq, NULL);
+static DEVICE_ATTR(freq, S_IWUGO | S_IRUGO,
+ ep93xx_pwm_get_freq, ep93xx_pwm_set_freq);
+static DEVICE_ATTR(duty_percent, S_IWUGO | S_IRUGO,
+ ep93xx_pwm_get_duty_percent, ep93xx_pwm_set_duty_percent);
+static DEVICE_ATTR(invert, S_IWUGO | S_IRUGO,
+ ep93xx_pwm_get_invert, ep93xx_pwm_set_invert);
+
+static struct attribute *ep93xx_pwm_attrs[] = {
+ &dev_attr_min_freq.attr,
+ &dev_attr_max_freq.attr,
+ &dev_attr_freq.attr,
+ &dev_attr_duty_percent.attr,
+ &dev_attr_invert.attr,
+ NULL
+};
+
+static const struct attribute_group ep93xx_pwm_sysfs_files = {
+ .attrs = ep93xx_pwm_attrs,
+};
+
+static int __init ep93xx_pwm_probe(struct platform_device *pdev)
+{
+ struct ep93xx_pwm *pwm;
+ struct resource *res;
+ int err;
+
+ err = ep93xx_pwm_acquire_gpio(pdev);
+ if (err)
+ return err;
+
+ pwm = kzalloc(sizeof(struct ep93xx_pwm), GFP_KERNEL);
+ if (!pwm) {
+ err = -ENOMEM;
+ goto fail_no_mem;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (res == NULL) {
+ err = -ENXIO;
+ goto fail_no_mem_resource;
+ }
+
+ res = request_mem_region(res->start, resource_size(res), pdev->name);
+ if (res == NULL) {
+ err = -EBUSY;
+ goto fail_no_mem_resource;
+ }
+
+ pwm->mmio_base = ioremap(res->start, resource_size(res));
+ if (pwm->mmio_base == NULL) {
+ err = -ENXIO;
+ goto fail_no_ioremap;
+ }
+
+ err = sysfs_create_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
+ if (err)
+ goto fail_no_sysfs;
+
+ pwm->clk = clk_get(&pdev->dev, "pwm_clk");
+ if (IS_ERR(pwm->clk)) {
+ err = PTR_ERR(pwm->clk);
+ goto fail_no_clk;
+ }
+
+ pwm->duty_percent = 50;
+
+ platform_set_drvdata(pdev, pwm);
+
+ /* disable pwm at startup. Avoids zero value. */
+ ep93xx_pwm_disable(pwm);
+ ep93xx_pwm_write_tc(pwm, EP93XX_PWM_MAX_COUNT);
+ ep93xx_pwm_write_dc(pwm, EP93XX_PWM_MAX_COUNT / 2);
+
+ clk_enable(pwm->clk);
+
+ return 0;
+
+fail_no_clk:
+ sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
+fail_no_sysfs:
+ iounmap(pwm->mmio_base);
+fail_no_ioremap:
+ release_mem_region(res->start, resource_size(res));
+fail_no_mem_resource:
+ kfree(pwm);
+fail_no_mem:
+ ep93xx_pwm_release_gpio(pdev);
+ return err;
+}
+
+static int __exit ep93xx_pwm_remove(struct platform_device *pdev)
+{
+ struct ep93xx_pwm *pwm = platform_get_drvdata(pdev);
+ struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+ ep93xx_pwm_disable(pwm);
+ clk_disable(pwm->clk);
+ clk_put(pwm->clk);
+ platform_set_drvdata(pdev, NULL);
+ sysfs_remove_group(&pdev->dev.kobj, &ep93xx_pwm_sysfs_files);
+ iounmap(pwm->mmio_base);
+ release_mem_region(res->start, resource_size(res));
+ kfree(pwm);
+ ep93xx_pwm_release_gpio(pdev);
+
+ return 0;
+}
+
+static struct platform_driver ep93xx_pwm_driver = {
+ .driver = {
+ .name = "ep93xx-pwm",
+ .owner = THIS_MODULE,
+ },
+ .remove = __exit_p(ep93xx_pwm_remove),
+};
+
+static int __init ep93xx_pwm_init(void)
+{
+ return platform_driver_probe(&ep93xx_pwm_driver, ep93xx_pwm_probe);
+}
+
+static void __exit ep93xx_pwm_exit(void)
+{
+ platform_driver_unregister(&ep93xx_pwm_driver);
+}
+
+module_init(ep93xx_pwm_init);
+module_exit(ep93xx_pwm_exit);
+
+MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>, "
+ "H Hartley Sweeten <hsweeten@visionengravers.com>");
+MODULE_DESCRIPTION("EP93xx PWM driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ep93xx-pwm");