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>

3 files changed, 398 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 68ab39d7cb35..df1f86b5c83e 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -233,6 +233,19 @@ config ISL29003
           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 36f733cd60e6..f982d2ecfde7 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_SGI_XP)		+= sgi-xp/
 obj-$(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 000000000000..ba4694169d79
--- /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");