misc: Add ab8500 pwm driver

This patch adds a Pulse Width Modulation driver for Analog Baseband
Chip AB8500.

Signed-off-by: Arun Murthy <arun.murthy@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

3 files changed, 178 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 39a2173b4e6c..4d073f1e4502 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -62,6 +62,15 @@ config ATMEL_PWM
           purposes including software controlled power-efficient backlights
           on LCD displays, motor control, and waveform generation.
 
+config AB8500_PWM
+        bool "AB8500 PWM support"
+        depends on AB8500_CORE
+        select HAVE_PWM
+        help
+          This driver exports functions to enable/disble/config/free Pulse
+          Width Modulation in the Analog Baseband Chip AB8500.
+          It is used by led and backlight driver to control the intensity.
+
 config ATMEL_TCLIB
         bool "Atmel AT32/AT91 Timer/Counter Library"
         depends on (AVR32 || ARCH_AT91)
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 47af4cd08f01..98009cc20cb9 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -41,3 +41,4 @@ obj-$(CONFIG_VMWARE_BALLOON)	+= vmw_balloon.o
 obj-$(CONFIG_ARM_CHARLCD)       += arm-charlcd.o
 obj-$(CONFIG_PCH_PHUB)          += pch_phub.o
 obj-y                           += ti-st/
+obj-$(CONFIG_AB8500_PWM)        += ab8500-pwm.o
diff --git a/drivers/misc/ab8500-pwm.c b/drivers/misc/ab8500-pwm.c
new file mode 100644
index 000000000000..54e3d05b63cc
--- /dev/null
+++ b/drivers/misc/ab8500-pwm.c
@@ -0,0 +1,168 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Author: Arun R Murthy <arun.murthy@stericsson.com>
+ * License terms: GNU General Public License (GPL) version 2
+ */
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/pwm.h>
+#include <linux/mfd/ab8500.h>
+#include <linux/mfd/abx500.h>
+
+/*
+ * PWM Out generators
+ * Bank: 0x10
+ */
+#define AB8500_PWM_OUT_CTRL1_REG        0x60
+#define AB8500_PWM_OUT_CTRL2_REG        0x61
+#define AB8500_PWM_OUT_CTRL7_REG        0x66
+
+/* backlight driver constants */
+#define ENABLE_PWM                      1
+#define DISABLE_PWM                     0
+
+struct pwm_device {
+        struct device *dev;
+        struct list_head node;
+        const char *label;
+        unsigned int pwm_id;
+};
+
+static LIST_HEAD(pwm_list);
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+        int ret = 0;
+        unsigned int higher_val, lower_val;
+        u8 reg;
+
+        /*
+         * get the first 8 bits that are be written to
+         * AB8500_PWM_OUT_CTRL1_REG[0:7]
+         */
+        lower_val = duty_ns & 0x00FF;
+        /*
+         * get bits [9:10] that are to be written to
+         * AB8500_PWM_OUT_CTRL2_REG[0:1]
+         */
+        higher_val = ((duty_ns & 0x0300) >> 8);
+
+        reg = AB8500_PWM_OUT_CTRL1_REG + ((pwm->pwm_id - 1) * 2);
+
+        ret = abx500_set_register_interruptible(pwm->dev, AB8500_MISC,
+                        reg, (u8)lower_val);
+        if (ret < 0)
+                return ret;
+        ret = abx500_set_register_interruptible(pwm->dev, AB8500_MISC,
+                        (reg + 1), (u8)higher_val);
+
+        return ret;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+        int ret;
+
+        ret = abx500_mask_and_set_register_interruptible(pwm->dev,
+                                AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
+                                1 << (pwm->pwm_id-1), ENABLE_PWM);
+        if (ret < 0)
+                dev_err(pwm->dev, "%s: Failed to disable PWM, Error %d\n",
+                                                        pwm->label, ret);
+        return ret;
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+        int ret;
+
+        ret = abx500_mask_and_set_register_interruptible(pwm->dev,
+                                AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
+                                1 << (pwm->pwm_id-1), DISABLE_PWM);
+        if (ret < 0)
+                dev_err(pwm->dev, "%s: Failed to disable PWM, Error %d\n",
+                                                        pwm->label, ret);
+        return;
+}
+EXPORT_SYMBOL(pwm_disable);
+
+struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+        struct pwm_device *pwm;
+
+        list_for_each_entry(pwm, &pwm_list, node) {
+                if (pwm->pwm_id == pwm_id) {
+                        pwm->label = label;
+                        pwm->pwm_id = pwm_id;
+                        return pwm;
+                }
+        }
+
+        return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL(pwm_request);
+
+void pwm_free(struct pwm_device *pwm)
+{
+        pwm_disable(pwm);
+}
+EXPORT_SYMBOL(pwm_free);
+
+static int __devinit ab8500_pwm_probe(struct platform_device *pdev)
+{
+        struct pwm_device *pwm;
+        /*
+         * Nothing to be done in probe, this is required to get the
+         * device which is required for ab8500 read and write
+         */
+        pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
+        if (pwm == NULL) {
+                dev_err(&pdev->dev, "failed to allocate memory\n");
+                return -ENOMEM;
+        }
+        pwm->dev = &pdev->dev;
+        pwm->pwm_id = pdev->id;
+        list_add_tail(&pwm->node, &pwm_list);
+        platform_set_drvdata(pdev, pwm);
+        dev_dbg(pwm->dev, "pwm probe successful\n");
+        return 0;
+}
+
+static int __devexit ab8500_pwm_remove(struct platform_device *pdev)
+{
+        struct pwm_device *pwm = platform_get_drvdata(pdev);
+        list_del(&pwm->node);
+        dev_dbg(&pdev->dev, "pwm driver removed\n");
+        kfree(pwm);
+        return 0;
+}
+
+static struct platform_driver ab8500_pwm_driver = {
+        .driver = {
+                .name = "ab8500-pwm",
+                .owner = THIS_MODULE,
+        },
+        .probe = ab8500_pwm_probe,
+        .remove = __devexit_p(ab8500_pwm_remove),
+};
+
+static int __init ab8500_pwm_init(void)
+{
+        return platform_driver_register(&ab8500_pwm_driver);
+}
+
+static void __exit ab8500_pwm_exit(void)
+{
+        platform_driver_unregister(&ab8500_pwm_driver);
+}
+
+subsys_initcall(ab8500_pwm_init);
+module_exit(ab8500_pwm_exit);
+MODULE_AUTHOR("Arun MURTHY <arun.murthy@stericsson.com>");
+MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
+MODULE_ALIAS("AB8500 PWM driver");
+MODULE_LICENSE("GPL v2");