Patchwork [RFC,4/6,PWM] Driver for Atmel PWMC peripheral

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Submitter Bill Gatliff
Date Oct. 8, 2008, 4:43 p.m.
Message ID <5640f37b779f953c83e79c16b2a0466c0f5da702.1223482372.git.bgat@billgatliff.com>
Download mbox | patch
Permalink /patch/3330/
State Not Applicable
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Comments

Bill Gatliff - Oct. 8, 2008, 4:43 p.m.
Signed-off-by: Bill Gatliff <bgat@billgatliff.com>
---
 drivers/pwm/atmel-pwm.c |  631 +++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 631 insertions(+), 0 deletions(-)
 create mode 100644 drivers/pwm/atmel-pwm.c

Patch

diff --git a/drivers/pwm/atmel-pwm.c b/drivers/pwm/atmel-pwm.c
new file mode 100644
index 0000000..b65e84f
--- /dev/null
+++ b/drivers/pwm/atmel-pwm.c
@@ -0,0 +1,631 @@ 
+/*
+ * drivers/pwm/atmel-pwm.c
+ *
+ * Copyright (C) 2008 Bill Gatliff
+ * Copyright (C) 2007 David Brownell
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+
+enum {
+	/* registers common to the PWMC peripheral */
+	PWMC_MR = 0,
+	PWMC_ENA = 4,
+	PWMC_DIS = 8,
+	PWMC_SR = 0xc,
+	PWMC_IER = 0x10,
+	PWMC_IDR = 0x14,
+	PWMC_IMR = 0x18,
+	PWMC_ISR = 0x1c,
+
+	/* registers per each PWMC channel */
+	PWMC_CMR = 0,
+	PWMC_CDTY = 4,
+	PWMC_CPRD = 8,
+	PWMC_CCNT = 0xc,
+	PWMC_CUPD = 0x10,
+
+	/* how to find each channel */
+	PWMC_CHAN_BASE = 0x200,
+	PWMC_CHAN_STRIDE = 0x20,
+
+	/* CMR bits of interest */
+	PWMC_CMR_CPD = 10,
+	PWMC_CMR_CPOL = 9,
+	PWMC_CMR_CALG = 8,
+	PWMC_CMR_CPRE_MASK = 0xf,
+};
+
+struct atmel_pwm {
+	struct pwm_device pwm;
+	spinlock_t lock;
+	void __iomem *iobase;
+	struct clk *clk;
+	u32 *sync_mask;
+	int irq;
+	u32 ccnt_mask;
+};
+
+
+static inline void
+pwmc_writel(const struct atmel_pwm *p,
+	    unsigned offset, u32 val)
+{
+	__raw_writel(val, p->iobase + offset);
+}
+
+
+static inline u32
+pwmc_readl(const struct atmel_pwm *p,
+	   unsigned offset)
+{
+	return __raw_readl(p->iobase + offset);
+}
+
+
+static inline void
+pwmc_chan_writel(const struct pwm_channel *p,
+		 u32 offset, u32 val)
+{
+	const struct atmel_pwm *ap
+		= container_of(p->pwm, struct atmel_pwm, pwm);
+
+	if (PWMC_CMR == offset)
+		val &= ((1 << PWMC_CMR_CPD)
+			| (1 << PWMC_CMR_CPOL)
+			| (1 << PWMC_CMR_CALG)
+			| (PWMC_CMR_CPRE_MASK));
+	else
+		val &= ap->ccnt_mask;
+
+	pwmc_writel(ap, offset + PWMC_CHAN_BASE
+		    + (p->chan * PWMC_CHAN_STRIDE), val);
+}
+
+
+static inline u32
+pwmc_chan_readl(const struct pwm_channel *p,
+		u32 offset)
+{
+	const struct atmel_pwm *ap
+		= container_of(p->pwm, struct atmel_pwm, pwm);
+
+	return pwmc_readl(ap, offset + PWMC_CHAN_BASE
+			  + (p->chan * PWMC_CHAN_STRIDE));
+}
+
+
+static inline int
+__atmel_pwm_is_on(struct pwm_channel *p)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	return (pwmc_readl(ap, PWMC_SR) & (1 << p->chan)) ? 1 : 0;
+}
+
+
+static inline void
+__atmel_pwm_unsynchronize(struct pwm_channel *p,
+			  struct pwm_channel *to_p)
+{
+	const struct atmel_pwm *ap
+		= container_of(p->pwm, struct atmel_pwm, pwm);
+	int wchan;
+
+	if (to_p) {
+		ap->sync_mask[p->chan] &= ~(1 << to_p->chan);
+		ap->sync_mask[to_p->chan] &= ~(1 << p->chan);
+		goto done;
+	}
+
+	ap->sync_mask[p->chan] = 0;
+	for (wchan = 0; wchan < ap->pwm.nchan; wchan++)
+		ap->sync_mask[wchan] &= ~(1 << p->chan);
+done:
+	pr_debug("%s:%d sync_mask %x\n",
+		 p->pwm->bus_id, p->chan, ap->sync_mask[p->chan]);
+}
+
+
+static inline void
+__atmel_pwm_synchronize(struct pwm_channel *p,
+			struct pwm_channel *to_p)
+{
+	const struct atmel_pwm *ap
+		= container_of(p->pwm, struct atmel_pwm, pwm);
+
+	if (!to_p)
+		return;
+
+	ap->sync_mask[p->chan] |= (1 << to_p->chan);
+	ap->sync_mask[to_p->chan] |= (1 << p->chan);
+
+	pr_debug("%s:%d sync_mask %x\n",
+		 p->pwm->bus_id, p->chan, ap->sync_mask[p->chan]);
+}
+
+
+static inline void
+__atmel_pwm_stop(struct pwm_channel *p)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	u32 chid = 1 << p->chan;
+
+	pwmc_writel(ap, PWMC_DIS, ap->sync_mask[p->chan] | chid);
+}
+
+
+static inline void
+__atmel_pwm_start(struct pwm_channel *p)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	u32 chid = 1 << p->chan;
+
+	pwmc_writel(ap, PWMC_ENA, ap->sync_mask[p->chan] | chid);
+}
+
+
+static int
+atmel_pwm_synchronize(struct pwm_channel *p,
+		      struct pwm_channel *to_p)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&p->lock, flags);
+	__atmel_pwm_synchronize(p, to_p);
+	spin_unlock_irqrestore(&p->lock, flags);
+	return 0;
+}
+
+
+static int
+atmel_pwm_unsynchronize(struct pwm_channel *p,
+			struct pwm_channel *from_p)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&p->lock, flags);
+	__atmel_pwm_unsynchronize(p, from_p);
+	spin_unlock_irqrestore(&p->lock, flags);
+	return 0;
+}
+
+
+static inline int
+__atmel_pwm_config_polarity(struct pwm_channel *p,
+			    struct pwm_channel_config *c)
+{
+	u32 cmr = pwmc_chan_readl(p, PWMC_CMR);
+
+	if (c->polarity)
+		cmr &= ~BIT(PWMC_CMR_CPOL);
+	else
+		cmr |= BIT(PWMC_CMR_CPOL);
+	pwmc_chan_writel(p, PWMC_CMR, cmr);
+
+	pr_debug("%s:%d polarity %d\n", p->pwm->bus_id,
+		 p->chan, c->polarity);
+	return 0;
+}
+
+
+static inline int
+__atmel_pwm_config_duty_ticks(struct pwm_channel *p,
+			      struct pwm_channel_config *c)
+{
+	u32 cmr, cprd, cpre, cdty;
+
+	cmr = pwmc_chan_readl(p, PWMC_CMR);
+	cprd = pwmc_chan_readl(p, PWMC_CPRD);
+
+	cpre = cmr & PWMC_CMR_CPRE_MASK;
+	cmr &= ~BIT(PWMC_CMR_CPD);
+
+	cdty = cprd - (c->duty_ticks >> cpre);
+
+	p->duty_ticks = c->duty_ticks;
+
+	if (__atmel_pwm_is_on(p)) {
+		pwmc_chan_writel(p, PWMC_CMR, cmr);
+		pwmc_chan_writel(p, PWMC_CUPD, cdty);
+	} else
+		pwmc_chan_writel(p, PWMC_CDTY, cdty);
+
+	pr_debug("%s:%d duty_ticks = %lu cprd = %x"
+		 " cdty = %x cpre = %x\n",
+		 p->pwm->bus_id, p->chan, p->duty_ticks,
+		 cprd, cdty, cpre);
+
+	return 0;
+}
+
+
+static inline int
+__atmel_pwm_config_period_ticks(struct pwm_channel *p,
+				struct pwm_channel_config *c)
+{
+	u32 cmr, cprd, cpre;
+
+	cpre = fls(c->period_ticks);
+	if (cpre < 16)
+		cpre = 0;
+	else {
+		cpre -= 15;
+		if (cpre > 10)
+			return -EINVAL;
+	}
+
+	cmr = pwmc_chan_readl(p, PWMC_CMR);
+	cmr &= ~PWMC_CMR_CPRE_MASK;
+	cmr |= cpre;
+
+	cprd = c->period_ticks >> cpre;
+
+	pwmc_chan_writel(p, PWMC_CMR, cmr);
+	pwmc_chan_writel(p, PWMC_CPRD, cprd);
+	p->period_ticks = c->period_ticks;
+
+	pr_debug("%s:%d period_ticks = %lu cprd = %x cpre = %x\n",
+		 p->pwm->bus_id, p->chan, p->period_ticks, cprd, cpre);
+
+	return 0;
+}
+
+
+
+static int
+atmel_pwm_config_nosleep(struct pwm_channel *p,
+			 struct pwm_channel_config *c)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&p->lock, flags);
+
+	switch (c->config_mask) {
+
+	case PWM_CONFIG_DUTY_TICKS:
+		__atmel_pwm_config_duty_ticks(p, c);
+		break;
+
+	case PWM_CONFIG_STOP:
+		__atmel_pwm_stop(p);
+		pr_debug("%s:%d stop\n", p->pwm->bus_id, p->chan);
+		break;
+
+	case PWM_CONFIG_START:
+		__atmel_pwm_start(p);
+		pr_debug("%s:%d start\n", p->pwm->bus_id, p->chan);
+		break;
+
+	case PWM_CONFIG_POLARITY:
+		__atmel_pwm_config_polarity(p, c);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	spin_unlock_irqrestore(&p->lock, flags);
+	return ret;
+}
+
+
+static int
+atmel_pwm_stop_sync(struct pwm_channel *p)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	int ret;
+	int was_on = __atmel_pwm_is_on(p);
+
+	if (was_on) {
+		do {
+			init_completion(&p->complete);
+			set_bit(FLAG_STOP, &p->flags);
+			pwmc_writel(ap, PWMC_IER, 1 << p->chan);
+
+			pr_debug("%s:%d waiting on stop_sync completion...\n",
+				 p->pwm->bus_id, p->chan);
+
+			ret = wait_for_completion_interruptible(&p->complete);
+
+			pr_debug("%s:%d stop_sync complete (%d)\n",
+				 p->pwm->bus_id, p->chan, ret);
+
+			if (ret)
+				return ret;
+		} while (p->flags & BIT(FLAG_STOP));
+	}
+
+	pr_debug("%s:%d stop_sync returning %d\n",
+		 p->pwm->bus_id, p->chan, was_on);
+
+	return was_on;
+}
+
+
+static int
+atmel_pwm_config(struct pwm_channel *p,
+		 struct pwm_channel_config *c)
+{
+	int was_on = 0;
+
+	might_sleep();
+
+	if (p->pwm->config_nosleep) {
+		if (!p->pwm->config_nosleep(p, c))
+			return 0;
+	}
+
+	pr_debug("%s:%d config_mask %x\n",
+		 p->pwm->bus_id, p->chan, c->config_mask);
+
+	was_on = atmel_pwm_stop_sync(p);
+	if (was_on < 0)
+		return was_on;
+
+	if (c->config_mask & PWM_CONFIG_PERIOD_TICKS) {
+		__atmel_pwm_config_period_ticks(p, c);
+		if (!(c->config_mask & PWM_CONFIG_DUTY_TICKS)) {
+			struct pwm_channel_config d = {
+				.config_mask = PWM_CONFIG_DUTY_TICKS,
+				.duty_ticks = p->duty_ticks,
+			};
+			__atmel_pwm_config_duty_ticks(p, &d);
+		}
+	}
+
+	if (c->config_mask & PWM_CONFIG_DUTY_TICKS)
+		__atmel_pwm_config_duty_ticks(p, c);
+
+	if (c->config_mask & PWM_CONFIG_POLARITY)
+		__atmel_pwm_config_polarity(p, c);
+
+	if ((c->config_mask & PWM_CONFIG_START)
+	    || (was_on && !(c->config_mask & PWM_CONFIG_STOP)))
+		__atmel_pwm_start(p);
+
+	return 0;
+}
+
+
+static void
+__atmel_pwm_set_callback(struct pwm_channel *p,
+			 pwm_callback_t callback)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+
+	p->callback = callback;
+	pwmc_writel(ap, p->callback ? PWMC_IER : PWMC_IDR, 1 << p->chan);
+	pr_debug("%s:%d set_callback %p\n", p->pwm->bus_id, p->chan, callback);
+}
+
+
+static int
+atmel_pwm_set_callback(struct pwm_channel *p,
+		       pwm_callback_t callback)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ap->lock, flags);
+	__atmel_pwm_set_callback(p, callback);
+	spin_unlock_irqrestore(&ap->lock, flags);
+
+	return 0;
+}
+
+
+static int
+atmel_pwm_request(struct pwm_channel *p)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	unsigned long flags;
+
+	spin_lock_irqsave(&p->lock, flags);
+	clk_enable(ap->clk);
+	p->tick_hz = clk_get_rate(ap->clk);
+	__atmel_pwm_unsynchronize(p, NULL);
+	__atmel_pwm_stop(p);
+	spin_unlock_irqrestore(&p->lock, flags);
+
+	return 0;
+}
+
+
+static void
+atmel_pwm_free(struct pwm_channel *p)
+{
+	struct atmel_pwm *ap = container_of(p->pwm, struct atmel_pwm, pwm);
+	clk_disable(ap->clk);
+}
+
+
+static irqreturn_t
+atmel_pwmc_irq(int irq, void *data)
+{
+	struct atmel_pwm *ap = data;
+	struct pwm_channel *p;
+	u32 isr;
+	int chid;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ap->lock, flags);
+
+	isr = pwmc_readl(ap, PWMC_ISR);
+	for (chid = 0; isr; chid++, isr >>= 1) {
+		p = &ap->pwm.channels[chid];
+		if (isr & 1) {
+			if (p->callback)
+				p->callback(p);
+			if (p->flags & BIT(FLAG_STOP)) {
+				__atmel_pwm_stop(p);
+				clear_bit(FLAG_STOP, &p->flags);
+			}
+			complete_all(&p->complete);
+		}
+	}
+
+	spin_unlock_irqrestore(&ap->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+
+static int __init
+atmel_pwmc_probe(struct platform_device *pdev)
+{
+	struct atmel_pwm *ap;
+	struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	int ret = 0;
+
+	ap = kzalloc(sizeof(*ap), GFP_KERNEL);
+	if (!ap) {
+		ret = -ENOMEM;
+		goto err_atmel_pwm_alloc;
+	}
+
+	spin_lock_init(&ap->lock);
+	platform_set_drvdata(pdev, ap);
+
+	ap->pwm.bus_id = pdev->dev.bus_id;
+
+	ap->pwm.nchan = 4; /* TODO: true only for SAM9263 and AP7000 */
+	ap->ccnt_mask = 0xffffUL; /* TODO: true only for SAM9263 */
+
+	ap->sync_mask = kzalloc(ap->pwm.nchan * sizeof(u32), GFP_KERNEL);
+	if (!ap->sync_mask) {
+		ret = -ENOMEM;
+		goto err_alloc_sync_masks;
+	}
+
+	ap->pwm.owner = THIS_MODULE;
+	ap->pwm.request = atmel_pwm_request;
+	ap->pwm.free = atmel_pwm_free;
+	ap->pwm.config_nosleep = atmel_pwm_config_nosleep;
+	ap->pwm.config = atmel_pwm_config;
+	ap->pwm.synchronize = atmel_pwm_synchronize;
+	ap->pwm.unsynchronize = atmel_pwm_unsynchronize;
+	ap->pwm.set_callback = atmel_pwm_set_callback;
+
+	ap->clk = clk_get(&pdev->dev, "pwmc_clk");
+	if (!ap->clk) {
+		ret = -ENODEV;
+		goto err_clk_get;
+	}
+
+	ap->iobase = ioremap_nocache(r->start, r->end - r->start + 1);
+	if (!ap->iobase) {
+		ret = -ENODEV;
+		goto err_ioremap;
+	}
+
+	clk_enable(ap->clk);
+	pwmc_writel(ap, PWMC_DIS, -1);
+	pwmc_writel(ap, PWMC_IDR, -1);
+	clk_disable(ap->clk);
+
+	ap->irq = platform_get_irq(pdev, 0);
+	if (ap->irq != -ENXIO) {
+		ret = request_irq(ap->irq, atmel_pwmc_irq, 0,
+				  ap->pwm.bus_id, ap);
+		if (ret)
+			goto err_request_irq;
+	}
+
+	ret = pwm_register(&ap->pwm);
+	if (ret)
+		goto err_pwm_register;
+
+	return 0;
+
+err_pwm_register:
+	if (ap->irq != -ENXIO)
+		free_irq(ap->irq, ap);
+err_request_irq:
+	iounmap(ap->iobase);
+err_ioremap:
+	clk_put(ap->clk);
+err_clk_get:
+	platform_set_drvdata(pdev, NULL);
+err_alloc_sync_masks:
+	kfree(ap);
+err_atmel_pwm_alloc:
+	return ret;
+}
+
+
+static int __devexit
+atmel_pwmc_remove(struct platform_device *pdev)
+{
+	struct atmel_pwm *ap = platform_get_drvdata(pdev);
+	int ret;
+
+	/* TODO: what can we do if this fails? */
+	ret = pwm_unregister(&ap->pwm);
+
+	clk_enable(ap->clk);
+	pwmc_writel(ap, PWMC_IDR, -1);
+	pwmc_writel(ap, PWMC_DIS, -1);
+	clk_disable(ap->clk);
+
+	if (ap->irq != -ENXIO)
+		free_irq(ap->irq, ap);
+
+	clk_put(ap->clk);
+	iounmap(ap->iobase);
+
+	kfree(ap);
+
+	return 0;
+}
+
+
+static struct platform_driver atmel_pwm_driver = {
+	.driver = {
+		.name = "atmel_pwmc",
+		.owner = THIS_MODULE,
+	},
+	.probe = atmel_pwmc_probe,
+	.remove = __devexit_p(atmel_pwmc_remove),
+};
+
+
+static int __init atmel_pwm_init(void)
+{
+	return platform_driver_register(&atmel_pwm_driver);
+}
+module_init(atmel_pwm_init);
+
+
+static void atmel_pwm_exit(void)
+{
+	platform_driver_unregister(&atmel_pwm_driver);
+}
+module_exit(atmel_pwm_exit);
+
+
+MODULE_AUTHOR("Bill Gatliff <bgat@billgatliff.com>");
+MODULE_DESCRIPTION("Driver for Atmel PWMC peripheral");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:atmel_pwmc");