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Date: Wed, 01 Sep 2010 08:19:39 +0300
From: Mike Rapoport <mike@...pulab.co.il>
To: Arun Murthy <arun.murthy@...ricsson.com>
CC: sameo@...ux.intel.com, riku.voipio@....fi,
linux-kernel@...r.kernel.org, STEricsson_nomadik_linux@...t.st.com,
Mike Rapoport <mike@...pulab.co.il>
Subject: Re: [PATCH v2] u8500: ab8500-pwm: Add pwm driver
Arun Murthy wrote:
> This patch adds a Pulse Width Modulation driver for Analog Baseband
> Chip AB8500.
>
> Signed-off-by: Arun Murthy <arun.murthy@...ricsson.com>
> Acked-by: Linus Walleij <linus.walleij@...ricsson.com>
> ---
> 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@...ricsson.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_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@...ricsson.com>");
> +MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
> +MODULE_ALIAS("AB8500 PWM driver");
> +MODULE_LICENSE("GPL v2");
--
Sincerely yours,
Mike.
--
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