[2/2] pwm: Add a i.MX23/28 pwm driver
diff mbox series

Message ID 1309255368-9775-3-git-send-email-s.hauer@pengutronix.de
State New, archived
Headers show
Series
  • [RFC] implement a generic PWM framework - once again
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Commit Message

Sascha Hauer June 28, 2011, 10:02 a.m. UTC
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/pwm/mxs-pwm.c |  275 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 275 insertions(+), 0 deletions(-)
 create mode 100644 drivers/pwm/mxs-pwm.c

Comments

Lothar Waßmann June 28, 2011, 10:28 a.m. UTC | #1
Hi,

just some nitpicks...

Sascha Hauer writes:
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/pwm/mxs-pwm.c |  275 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 275 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/pwm/mxs-pwm.c
> 
> diff --git a/drivers/pwm/mxs-pwm.c b/drivers/pwm/mxs-pwm.c
> new file mode 100644
> index 0000000..052cb0c
> --- /dev/null
> +++ b/drivers/pwm/mxs-pwm.c
> @@ -0,0 +1,275 @@
> +/*
> + * Copyright (C) 2011 Pengutronix
> + * Sascha Hauer <s.hauer@pengutronix.de>
> + *
> + * simple driver for PWM (Pulse Width Modulator) controller
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/pwm.h>
> +#include <mach/hardware.h>
> +#include <mach/mxs.h>
> +#include <mach/mx23.h>
> +#include <mach/mx28.h>
> +#include <asm/div64.h>
> +
> +struct mxs_pwm_device {
> +	struct device		*dev;
> +
> +	struct clk	*clk;
> +
> +	int		enabled;
> +	void __iomem	*mmio_base;
> +
> +	unsigned int	pwm_id;
> +
> +	u32		val_active;
> +	u32		val_period;
> +	int		period_us;
> +	struct pwm_chip chip;
> +};
> +
> +/* common register space */
> +static void __iomem *pwm_base_common;
> +#define REG_PWM_CTRL	0x0
> +#define PWM_SFTRST	(1 << 31)
> +#define PWM_CLKGATE	(1 << 30)
> +#define PWM_ENABLE(p)	(1 << (p))
> +
> +/* per pwm register space */
> +#define REG_ACTIVE	0x0
> +#define REG_PERIOD	0x10
> +
> +#define PERIOD_PERIOD(p)	((p) & 0xffff)
> +#define PERIOD_ACTIVE_HIGH	(3 << 16)
> +#define PERIOD_INACTIVE_LOW	(2 << 18)
> +#define PERIOD_CDIV(div)	(((div) & 0x7) << 20)
> +
[...]
> +static int __devinit mxs_pwm_probe(struct platform_device *pdev)
> +{
> +	struct mxs_pwm_device *pwm;
> +	struct resource *r;
> +	int ret = 0;
> +
> +	pwm = devm_kzalloc(&pdev->dev, sizeof(struct mxs_pwm_device), GFP_KERNEL);
> +	if (pwm == NULL) {
> +		dev_err(&pdev->dev, "failed to allocate memory\n");
> +		return -ENOMEM;
> +	}
> +
> +	pwm->clk = clk_get(&pdev->dev, NULL);
> +
> +	if (IS_ERR(pwm->clk)) {
Why an empty line here, but not in other similar places?

> +		ret = PTR_ERR(pwm->clk);
> +		goto err_free;
> +	}
> +
> +	pwm->chip.ops = &mxs_pwm_ops;
> +
> +	pwm->enabled = 0;
is already 0 due to kzalloc().

> +
> +	pwm->chip.pwm_id = pdev->id;
> +	pwm->chip.owner = THIS_MODULE;
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (r == NULL) {
> +		dev_err(&pdev->dev, "no memory resource defined\n");
> +		ret = -ENODEV;
> +		goto err_free_clk;
> +	}
> +
> +	r = request_mem_region(r->start, resource_size(r), pdev->name);
> +	if (r == NULL) {
> +		dev_err(&pdev->dev, "failed to request memory resource\n");
> +		ret = -EBUSY;
> +		goto err_free_clk;
> +	}
> +
> +	pwm->mmio_base = ioremap(r->start, resource_size(r));
> +	if (pwm->mmio_base == NULL) {
> +		dev_err(&pdev->dev, "failed to ioremap() registers\n");
> +		ret = -ENODEV;
-ENOMEM?.

> +	if (ret)
> +		goto err_free_mem;
> +
> +	platform_set_drvdata(pdev, pwm);
> +	return 0;
> +
> +err_free_mem:
> +	release_mem_region(r->start, resource_size(r));
> +err_free_clk:
> +	clk_put(pwm->clk);
> +err_free:
> +	kfree(pwm);
> +	return ret;
> +}
> +
> +static int __devexit mxs_pwm_remove(struct platform_device *pdev)
> +{
> +	struct mxs_pwm_device *pwm;
> +	struct resource *r;
> +	int ret;
> +
> +	pwm = platform_get_drvdata(pdev);
> +
> +	ret = pwmchip_remove(&pwm->chip);
> +	if (ret)
> +		return ret;
> +
> +	iounmap(pwm->mmio_base);
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	release_mem_region(r->start, resource_size(r));
> +
> +	clk_put(pwm->clk);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver mxs_pwm_driver = {
> +	.driver		= {
> +		.name	= "mxs-pwm",
> +	},
> +	.probe		= mxs_pwm_probe,
> +	.remove		= __devexit_p(mxs_pwm_remove),
> +};
> +
> +static int __init mxs_pwm_init(void)
> +{
> +	if (cpu_is_mx28())
> +		pwm_base_common = MX28_IO_ADDRESS(MX28_PWM_BASE_ADDR);
> +	else
> +		pwm_base_common = MX23_IO_ADDRESS(MX23_PWM_BASE_ADDR);
> +
> +	__mxs_clrl(PWM_SFTRST | PWM_CLKGATE, pwm_base_common + REG_PWM_CTRL);
> +
Shouldn't CLKGATE be set again in the remove() function?



Lothar Waßmann
Arnd Bergmann June 28, 2011, 3:22 p.m. UTC | #2
Hi Sascha,

On Tuesday 28 June 2011, Sascha Hauer wrote:
> +
> +/* common register space */
> +static void __iomem *pwm_base_common;
> +#define REG_PWM_CTRL   0x0
> +#define PWM_SFTRST     (1 << 31)
> +#define PWM_CLKGATE    (1 << 30)
> +#define PWM_ENABLE(p)  (1 << (p))
> +

The driver looks pretty good overall, but the global pwm_base_common register
is rather ugly. I think this should really be passed down through resources
from  the platform device in one way or another.

	Arnd
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Patch
diff mbox series

diff --git a/drivers/pwm/mxs-pwm.c b/drivers/pwm/mxs-pwm.c
new file mode 100644
index 0000000..052cb0c
--- /dev/null
+++ b/drivers/pwm/mxs-pwm.c
@@ -0,0 +1,275 @@ 
+/*
+ * Copyright (C) 2011 Pengutronix
+ * Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * simple driver for PWM (Pulse Width Modulator) controller
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/pwm.h>
+#include <mach/hardware.h>
+#include <mach/mxs.h>
+#include <mach/mx23.h>
+#include <mach/mx28.h>
+#include <asm/div64.h>
+
+struct mxs_pwm_device {
+	struct device		*dev;
+
+	struct clk	*clk;
+
+	int		enabled;
+	void __iomem	*mmio_base;
+
+	unsigned int	pwm_id;
+
+	u32		val_active;
+	u32		val_period;
+	int		period_us;
+	struct pwm_chip chip;
+};
+
+/* common register space */
+static void __iomem *pwm_base_common;
+#define REG_PWM_CTRL	0x0
+#define PWM_SFTRST	(1 << 31)
+#define PWM_CLKGATE	(1 << 30)
+#define PWM_ENABLE(p)	(1 << (p))
+
+/* per pwm register space */
+#define REG_ACTIVE	0x0
+#define REG_PERIOD	0x10
+
+#define PERIOD_PERIOD(p)	((p) & 0xffff)
+#define PERIOD_ACTIVE_HIGH	(3 << 16)
+#define PERIOD_INACTIVE_LOW	(2 << 18)
+#define PERIOD_CDIV(div)	(((div) & 0x7) << 20)
+
+static void pwm_update(struct mxs_pwm_device *pwm)
+{
+	writel(pwm->val_active, pwm->mmio_base + REG_ACTIVE);
+	writel(pwm->val_period, pwm->mmio_base + REG_PERIOD);
+}
+
+#define to_mxs_pwm_device(chip)	container_of(chip, struct mxs_pwm_device, chip)
+
+static int mxs_pwm_config(struct pwm_chip *chip, int duty_ns, int period_ns)
+{
+	struct mxs_pwm_device *pwm = to_mxs_pwm_device(chip);
+	int div = 0;
+	unsigned long rate;
+	unsigned long long c;
+	unsigned long period_cycles, duty_cycles;
+
+	rate = clk_get_rate(pwm->clk);
+
+	dev_dbg(pwm->dev, "config: duty_ns: %d, period_ns: %d (clkrate %ld)\n",
+			duty_ns, period_ns, rate);
+
+	while (1) {
+		c = rate / (1 << div);
+		c = c * period_ns;
+		do_div(c, 1000000000);
+		if (c < 0x10000)
+			break;
+		div++;
+
+		if (div > 8)
+			return -EINVAL;
+	}
+
+	period_cycles = c;
+	duty_cycles = period_cycles * duty_ns / period_ns;
+
+	dev_dbg(pwm->dev, "config period_cycles: %ld duty_cycles: %ld\n",
+			period_cycles, duty_cycles);
+
+	pwm->val_active = period_cycles << 16 | duty_cycles;
+	pwm->val_period = PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
+			PERIOD_INACTIVE_LOW | PERIOD_CDIV(div);
+	pwm->period_us = period_ns / 1000;
+
+	pwm_update(pwm);
+
+	return 0;
+}
+
+static void __pwm_enable(struct mxs_pwm_device *pwm, int enable)
+{
+	if (enable)
+		__mxs_setl(PWM_ENABLE(pwm->chip.pwm_id), pwm_base_common + REG_PWM_CTRL);
+	else
+		__mxs_clrl(PWM_ENABLE(pwm->chip.pwm_id), pwm_base_common + REG_PWM_CTRL);
+}
+
+static int mxs_pwm_enable(struct pwm_chip *chip)
+{
+	struct mxs_pwm_device *pwm = to_mxs_pwm_device(chip);
+	int ret = 0;
+
+	dev_dbg(pwm->dev, "enable\n");
+
+	if (!pwm->enabled) {
+		ret = clk_enable(pwm->clk);
+		if (!ret) {
+			pwm->enabled = 1;
+			__pwm_enable(pwm, 1);
+			pwm_update(pwm);
+		}
+	}
+	return ret;
+}
+
+static void mxs_pwm_disable(struct pwm_chip *chip)
+{
+	struct mxs_pwm_device *pwm = to_mxs_pwm_device(chip);
+
+	dev_dbg(pwm->dev, "disable\n");
+
+	if (pwm->enabled) {
+		/*
+		 * We need a little delay here, it takes one period for
+		 * the last pwm_config call to take effect. If we disable
+		 * the pwm too early it just freezes the current output
+		 * state.
+		 */
+		usleep_range(pwm->period_us, pwm->period_us * 2);
+		__pwm_enable(pwm, 0);
+		clk_disable(pwm->clk);
+		pwm->enabled = 0;
+	}
+}
+
+static struct pwm_ops mxs_pwm_ops = {
+	.enable = mxs_pwm_enable,
+	.disable = mxs_pwm_disable,
+	.config = mxs_pwm_config,
+};
+
+static int __devinit mxs_pwm_probe(struct platform_device *pdev)
+{
+	struct mxs_pwm_device *pwm;
+	struct resource *r;
+	int ret = 0;
+
+	pwm = devm_kzalloc(&pdev->dev, sizeof(struct mxs_pwm_device), GFP_KERNEL);
+	if (pwm == NULL) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	pwm->clk = clk_get(&pdev->dev, NULL);
+
+	if (IS_ERR(pwm->clk)) {
+		ret = PTR_ERR(pwm->clk);
+		goto err_free;
+	}
+
+	pwm->chip.ops = &mxs_pwm_ops;
+
+	pwm->enabled = 0;
+
+	pwm->chip.pwm_id = pdev->id;
+	pwm->chip.owner = THIS_MODULE;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "no memory resource defined\n");
+		ret = -ENODEV;
+		goto err_free_clk;
+	}
+
+	r = request_mem_region(r->start, resource_size(r), pdev->name);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "failed to request memory resource\n");
+		ret = -EBUSY;
+		goto err_free_clk;
+	}
+
+	pwm->mmio_base = ioremap(r->start, resource_size(r));
+	if (pwm->mmio_base == NULL) {
+		dev_err(&pdev->dev, "failed to ioremap() registers\n");
+		ret = -ENODEV;
+		goto err_free_mem;
+	}
+
+	ret = pwmchip_add(&pwm->chip);
+	if (ret)
+		goto err_free_mem;
+
+	platform_set_drvdata(pdev, pwm);
+	return 0;
+
+err_free_mem:
+	release_mem_region(r->start, resource_size(r));
+err_free_clk:
+	clk_put(pwm->clk);
+err_free:
+	kfree(pwm);
+	return ret;
+}
+
+static int __devexit mxs_pwm_remove(struct platform_device *pdev)
+{
+	struct mxs_pwm_device *pwm;
+	struct resource *r;
+	int ret;
+
+	pwm = platform_get_drvdata(pdev);
+
+	ret = pwmchip_remove(&pwm->chip);
+	if (ret)
+		return ret;
+
+	iounmap(pwm->mmio_base);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(r->start, resource_size(r));
+
+	clk_put(pwm->clk);
+
+	return 0;
+}
+
+static struct platform_driver mxs_pwm_driver = {
+	.driver		= {
+		.name	= "mxs-pwm",
+	},
+	.probe		= mxs_pwm_probe,
+	.remove		= __devexit_p(mxs_pwm_remove),
+};
+
+static int __init mxs_pwm_init(void)
+{
+	if (cpu_is_mx28())
+		pwm_base_common = MX28_IO_ADDRESS(MX28_PWM_BASE_ADDR);
+	else
+		pwm_base_common = MX23_IO_ADDRESS(MX23_PWM_BASE_ADDR);
+
+	__mxs_clrl(PWM_SFTRST | PWM_CLKGATE, pwm_base_common + REG_PWM_CTRL);
+
+	return platform_driver_register(&mxs_pwm_driver);
+}
+arch_initcall(mxs_pwm_init);
+
+static void __exit mxs_pwm_exit(void)
+{
+	platform_driver_unregister(&mxs_pwm_driver);
+}
+module_exit(mxs_pwm_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");