Re: [PATCH v2] u8500: ab8500-pwm: Add pwm driver
From: Mike Rapoport
Date: Wed Sep 01 2010 - 01:21:10 EST
Arun Murthy wrote:
This patch adds a Pulse Width Modulation driver for Analog Baseband
Chip AB8500.
Signed-off-by: Arun Murthy <arun.murthy@xxxxxxxxxxxxxx>
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
---
drivers/misc/Kconfig | 9 ++
drivers/misc/Makefile | 1 +
drivers/misc/ab8500-pwm.c | 195 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 205 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/ab8500-pwm.c
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 9df5b75..fcf2e7f 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 Ananlog 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 255a80d..33bc441 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -35,3 +35,4 @@ obj-y += eeprom/
obj-y += cb710/
obj-$(CONFIG_VMWARE_BALLOON) += vmware_balloon.o
obj-$(CONFIG_ARM_CHARLCD) += arm-charlcd.o
+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 0000000..258a2be
--- /dev/null
+++ b/drivers/misc/ab8500-pwm.c
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Author: Arun R Murthy <arun.murthy@xxxxxxxxxxxxxx>
+ * 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_CTRL3_REG 0x62
+#define AB8500_PWM_OUT_CTRL4_REG 0x63
+#define AB8500_PWM_OUT_CTRL5_REG 0x64
+#define AB8500_PWM_OUT_CTRL6_REG 0x65
+#define AB8500_PWM_OUT_CTRL7_REG 0x66
+
+/* backlight driver constants */
+#define ENABLE_PWM 1
+#define DISABLE_PWM 0
+
+static struct device *dev;
Is the static device pointer really necessary? Shouldn't it be encapsulated to
the driver info structure that is allocated during probe?
+struct pwm_device {
+ const char *label;
+ unsigned int pwm_id;
+};
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+ int ret = 0;
+ unsigned int higher_val, lower_val, pwm_val;
+
+ if (!dev)
+ return -EAGAIN;
+ /*
+ * 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);
+ switch (pwm->pwm_id) {
+ case 1:
+ /* pwm-1 */
+ ret = abx500_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL1_REG,
+ (u8)lower_val);
+ if (ret < 0)
+ return ret;
+ ret = abx500_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL2_REG,
+ (u8)higher_val);
+ break;
+ case 2:
+ /* pwm-2 */
+ ret = abx500_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL3_REG,
+ (u8)lower_val);
+ if (ret < 0)
+ return ret;
+ ret = abx500_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL4_REG,
+ (u8)higher_val);
+ break;
+ case 3:
+ /* pwm-3 */
+ ret = abx500_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL5_REG,
+ (u8)lower_val);
+ if (ret < 0)
+ return ret;
+ ret = abx500_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL6_REG,
+ (u8)higher_val);
+ break;
+ default:
+ dev_err(dev, "%s: invalid pwm entry = %d\n", __func__,
+ pwm->pwm_id);
+ return -EINVAL;
+ }
You can calculate the register address from the pwm_id and then the switch is
not needed, e.g.
reg = AB8500_PWM_OUT_CTRL1_REG + (pwm->pwm_id - 1) * 2;
ret = abx500_set_register_interruptible(dev, AB8500_MISC, reg,
(u8)lower_val);
if (ret < 0)
return ret;
ret = abx500_set_register_interruptible(dev, AB8500_MISC, reg + 1,
(u8)higher_val);
+ return ret;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+ int ret;
+
+ if (!dev)
+ return -EAGAIN;
+
+ ret = abx500_mask_and_set_register_interruptible(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
+ 1 << (pwm->pwm_id-1), ENABLE_PWM);
+ if (ret < 0)
+ dev_err(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(dev,
+ AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
+ 1 << (pwm->pwm_id-1), DISABLE_PWM);
+ if (ret < 0)
+ dev_err(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;
+
+ pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
+ if (pwm == NULL) {
+ dev_err(dev, "%s: failed to allocate memory\n", label);
+ return NULL;
+ }
+
+ pwm->label = label;
+ pwm->pwm_id = pwm_id;
+
+ return pwm;
+}
+EXPORT_SYMBOL(pwm_request);
+
+void pwm_free(struct pwm_device *pwm)
+{
+ pwm_disable(pwm);
+ kfree(pwm);
+}
+EXPORT_SYMBOL(pwm_free);
+
+static int __devinit ab8500_pwm_probe(struct platform_device *pdev)
+{
+ /*
+ * Nothing to be done in probe, this is required to get the
+ * device which is required for ab8500 read and write
+ */
+ dev = &pdev->dev;
+ dev_info(dev, "pwm probe successful\n");
dev_debug?
+ return 0;
+}
+
+static int __devexit ab8500_pwm_remove(struct platform_device *pdev)
+{
+ dev = NULL;
+ dev_info(&pdev->dev, "pwm driver removed\n");
dev_debug?
+ 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@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
+MODULE_ALIAS("AB8500 PWM driver");
+MODULE_LICENSE("GPL v2");
--
Sincerely yours,
Mike.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/