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Subject[PWM v8 3/3] PWM: Atmel PWMC driver
Date
Driver to allow the Atmel PWMC peripheral found on various
AT91 SoCs to be controlled using the Generic PWM framework.
Tested on the AT91SAM9263.

Signed-off-by: Bill Gatliff <bgat@billgatliff.com>
---
drivers/pwm/Kconfig | 8 +
drivers/pwm/Makefile | 1 +
drivers/pwm/atmel-pwmc.c | 452 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 461 insertions(+), 0 deletions(-)
create mode 100644 drivers/pwm/atmel-pwmc.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 476de67..560324a 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -19,3 +19,11 @@ config GPIO_PWM

To compile this feature as a module, chose M here; the module
will be called gpio-pwm. If unsure, say N.
+
+config ATMEL_PWMC
+ tristate "Atmel AT32/AT91 PWMC support"
+ depends on GENERIC_PWM && (AVR32 || ARCH_AT91SAM9263 || ARCH_AT91SAM9RL || ARCH_AT91CAP9)
+ help
+ This option enables support under the generic PWM
+ framework for PWMC peripheral channels found on
+ certain Atmel microcontrollers. If unsure, say N.
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index ecec3e4..d274fa0 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -4,3 +4,4 @@
obj-$(CONFIG_GENERIC_PWM) := pwm.o

obj-$(CONFIG_GPIO_PWM) += gpio-pwm.o
+obj-$(CONFIG_ATMEL_PWMC) += atmel-pwmc.o
diff --git a/drivers/pwm/atmel-pwmc.c b/drivers/pwm/atmel-pwmc.c
new file mode 100644
index 0000000..1339335
--- /dev/null
+++ b/drivers/pwm/atmel-pwmc.c
@@ -0,0 +1,452 @@
+/*
+ * Atmel PWMC peripheral driver
+ *
+ * Copyright (C) 2011 Bill Gatliff <bgat@billgatliff.com>
+ * Copyright (C) 2007 David Brownell
+ *
+ * This program is free software; you may redistribute and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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/slab.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/completion.h>
+#include <linux/pwm/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,
+};
+
+/* TODO: NCHAN==4 only for certain AT91-ish parts! */
+#define NCHAN 4
+struct atmel_pwmc {
+ struct pwm_device *p[NCHAN];
+ struct pwm_device_ops ops;
+ spinlock_t lock;
+ struct completion complete;
+ void __iomem *iobase;
+ struct clk *clk;
+ u32 ccnt_mask;
+};
+
+/* TODO: debugfs attributes for peripheral register values */
+
+static inline void pwmc_writel(const struct atmel_pwmc *p, unsigned offset, u32 val)
+{
+ __raw_writel(val, p->iobase + offset);
+}
+
+static inline u32 pwmc_readl(const struct atmel_pwmc *p, unsigned offset)
+{
+ return __raw_readl(p->iobase + offset);
+}
+
+static int __to_chan(const struct atmel_pwmc *ap, const struct pwm_device *p)
+{
+ int chan;
+ for (chan = 0; chan < NCHAN; chan++)
+ if (p == ap->p[chan])
+ return chan;
+ BUG();
+ return 0;
+}
+
+
+static void pwmc_chan_writel(const struct atmel_pwmc *ap, int chan, int offset, int val)
+{
+ 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
+ + (chan * PWMC_CHAN_STRIDE), val);
+}
+
+static u32 pwmc_chan_readl(const struct atmel_pwmc *ap, int chan, int offset)
+{
+ return pwmc_readl(ap, offset + PWMC_CHAN_BASE
+ + (chan * PWMC_CHAN_STRIDE));
+}
+
+static int __atmel_pwmc_is_on(const struct atmel_pwmc *ap, int chan)
+{
+ return (pwmc_readl(ap, PWMC_SR) & BIT(chan)) ? 1 : 0;
+}
+
+static void __atmel_pwmc_stop(const struct atmel_pwmc *ap, int chan)
+{
+ pwmc_writel(ap, PWMC_DIS, BIT(chan));
+}
+
+static void __atmel_pwmc_start(const struct atmel_pwmc *ap, int chan)
+{
+ pwmc_writel(ap, PWMC_ENA, BIT(chan));
+}
+
+static void __atmel_pwmc_config_polarity(struct atmel_pwmc *ap, int chan,
+ struct pwm_config *c)
+{
+ unsigned long cmr = pwmc_chan_readl(ap, chan, PWMC_CMR);
+ struct pwm_device *p = ap->p[chan];
+
+ if (c->polarity)
+ clear_bit(PWMC_CMR_CPOL, &cmr);
+ else
+ set_bit(PWMC_CMR_CPOL, &cmr);
+ pwmc_chan_writel(ap, chan, PWMC_CMR, cmr);
+ p->polarity = c->polarity ? 1 : 0;
+
+ dev_dbg(&p->dev, "polarity %d\n", c->polarity);
+}
+
+static void __atmel_pwmc_config_duty_ticks(struct atmel_pwmc *ap, int chan,
+ struct pwm_config *c)
+{
+ unsigned long cmr, cprd, cpre, cdty;
+ struct pwm_device *p = ap->p[chan];
+
+ cmr = pwmc_chan_readl(ap, chan, PWMC_CMR);
+ cprd = pwmc_chan_readl(ap, chan, PWMC_CPRD);
+
+ cpre = cmr & PWMC_CMR_CPRE_MASK;
+ clear_bit(PWMC_CMR_CPD, &cmr);
+
+ cdty = cprd - (c->duty_ticks >> cpre);
+
+ p->duty_ticks = c->duty_ticks;
+
+ if (__atmel_pwmc_is_on(ap, chan)) {
+ pwmc_chan_writel(ap, chan, PWMC_CMR, cmr);
+ pwmc_chan_writel(ap, chan, PWMC_CUPD, cdty);
+ } else
+ pwmc_chan_writel(ap, chan, PWMC_CDTY, cdty);
+
+ dev_dbg(&p->dev, "duty_ticks = %lu cprd = %lx"
+ " cdty = %lx cpre = %lx\n", p->duty_ticks,
+ cprd, cdty, cpre);
+}
+
+static int __atmel_pwmc_config_period_ticks(struct atmel_pwmc *ap, int chan,
+ struct pwm_config *c)
+{
+ u32 cmr, cprd, cpre;
+ struct pwm_device *p = ap->p[chan];
+
+ cpre = fls(c->period_ticks);
+ if (cpre < 16)
+ cpre = 0;
+ else {
+ cpre -= 15;
+ if (cpre > 10)
+ return -EINVAL;
+ }
+
+ cmr = pwmc_chan_readl(ap, chan, PWMC_CMR);
+ cmr &= ~PWMC_CMR_CPRE_MASK;
+ cmr |= cpre;
+
+ cprd = c->period_ticks >> cpre;
+
+ pwmc_chan_writel(ap, chan, PWMC_CMR, cmr);
+ pwmc_chan_writel(ap, chan, PWMC_CPRD, cprd);
+ p->period_ticks = c->period_ticks;
+
+ dev_dbg(&p->dev, "period_ticks = %lu cprd = %x cpre = %x\n",
+ p->period_ticks, cprd, cpre);
+ return 0;
+}
+
+static int atmel_pwmc_config_nosleep(struct pwm_device *p, struct pwm_config *c)
+{
+ struct atmel_pwmc *ap = pwm_get_drvdata(p);
+ int chan = __to_chan(ap, p);
+ int ret = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ap->lock, flags);
+
+ switch (c->config_mask) {
+
+ case BIT(PWM_CONFIG_DUTY_TICKS):
+ __atmel_pwmc_config_duty_ticks(ap, chan, c);
+ break;
+
+ case BIT(PWM_CONFIG_STOP):
+ __atmel_pwmc_stop(ap, chan);
+ break;
+
+ case BIT(PWM_CONFIG_START):
+ __atmel_pwmc_start(ap, chan);
+ break;
+
+ case BIT(PWM_CONFIG_POLARITY):
+ __atmel_pwmc_config_polarity(ap, chan, c);
+ break;
+
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ spin_unlock_irqrestore(&ap->lock, flags);
+ return ret;
+}
+
+static int atmel_pwmc_stop_sync(struct atmel_pwmc *ap, int chan)
+{
+ struct pwm_device *p = ap->p[chan];
+ int was_on = __atmel_pwmc_is_on(ap, chan);
+ int ret;
+
+ if (!was_on)
+ return 0;
+
+ do {
+ init_completion(&ap->complete);
+ set_bit(PWM_FLAG_STOP, &p->flags);
+ pwmc_writel(ap, PWMC_IER, BIT(chan));
+
+ dev_dbg(&p->dev, "waiting on stop_sync completion...\n");
+
+ ret = wait_for_completion_interruptible(&ap->complete);
+
+ dev_dbg(&p->dev, "stop_sync complete (%d)\n", ret);
+
+ if (ret)
+ return ret;
+ } while (test_bit(PWM_FLAG_STOP, &p->flags));
+
+ return 1;
+}
+
+static int atmel_pwmc_config(struct pwm_device *p, struct pwm_config *c)
+{
+ struct atmel_pwmc *ap = pwm_get_drvdata(p);
+ int chan = __to_chan(ap, p);
+ int was_on = 0;
+ int ret;
+
+
+ if (!atmel_pwmc_config_nosleep(p, c))
+ return 0;
+
+ might_sleep();
+
+ dev_dbg(&p->dev, "config_mask %lx\n", c->config_mask);
+
+ was_on = atmel_pwmc_stop_sync(ap, chan);
+ if (was_on < 0)
+ return was_on;
+
+ if (test_bit(PWM_CONFIG_PERIOD_TICKS, &c->config_mask)) {
+ ret = __atmel_pwmc_config_period_ticks(ap, chan, c);
+ if (ret)
+ return ret;
+
+ if (!test_bit(PWM_CONFIG_DUTY_TICKS, &c->config_mask)) {
+ struct pwm_config d = {
+ .config_mask = PWM_CONFIG_DUTY_TICKS,
+ .duty_ticks = p->duty_ticks,
+ };
+ __atmel_pwmc_config_duty_ticks(ap, chan, &d);
+ }
+ }
+
+ if (test_bit(PWM_CONFIG_DUTY_TICKS, &c->config_mask))
+ __atmel_pwmc_config_duty_ticks(ap, chan, c);
+
+ if (test_bit(PWM_CONFIG_POLARITY, &c->config_mask))
+ __atmel_pwmc_config_polarity(ap, chan, c);
+
+ if (test_bit(PWM_CONFIG_START, &c->config_mask)
+ || (was_on && !test_bit(PWM_CONFIG_STOP, &c->config_mask)))
+ __atmel_pwmc_start(ap, chan);
+
+ return 0;
+}
+
+static int atmel_pwmc_request(struct pwm_device *p)
+{
+ struct atmel_pwmc *ap = pwm_get_drvdata(p);
+ int chan = __to_chan(ap, p);
+ unsigned long flags;
+
+ spin_lock_irqsave(&ap->lock, flags);
+ clk_enable(ap->clk);
+ p->tick_hz = clk_get_rate(ap->clk);
+ __atmel_pwmc_stop(ap, chan);
+ spin_unlock_irqrestore(&ap->lock, flags);
+
+ return 0;
+}
+
+static void atmel_pwmc_release(struct pwm_device *p)
+{
+ struct atmel_pwmc *ap = pwm_get_drvdata(p);
+ clk_disable(ap->clk);
+}
+
+const struct pwm_device_ops atmel_pwm_ops = {
+ .request = atmel_pwmc_request,
+ .release = atmel_pwmc_release,
+ .config_nosleep = atmel_pwmc_config_nosleep,
+ .config = atmel_pwmc_config,
+ .owner = THIS_MODULE,
+};
+
+static int __devinit atmel_pwmc_probe(struct platform_device *pdev)
+{
+ struct atmel_pwmc *ap;
+ struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ signed int chan;
+ int ret = 0;
+
+ ap = kzalloc(sizeof(*ap), GFP_KERNEL);
+ if (!ap) {
+ ret = -ENOMEM;
+ goto err_atmel_pwmc_alloc;
+ }
+
+ spin_lock_init(&ap->lock);
+ init_completion(&ap->complete);
+ platform_set_drvdata(pdev, ap);
+
+ /* TODO: the datasheets are unclear as to how large CCNT
+ * actually is across all adopters of the PWMC; sixteen bits
+ * seems a safe assumption for now */
+ ap->ccnt_mask = 0xffffUL;
+
+ ap->clk = clk_get(&pdev->dev, "pwm_clk");
+ if (IS_ERR(ap->clk)) {
+ ret = -ENODEV;
+ goto err_clk_get;
+ }
+
+ ap->iobase = ioremap_nocache(r->start, resource_size(r));
+ 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);
+
+ for (chan = 0; chan < NCHAN; chan++) {
+ ap->p[chan] = pwm_register(&atmel_pwm_ops, &pdev->dev, "%s:%d",
+ dev_name(&pdev->dev), chan);
+ if (IS_ERR_OR_NULL(ap->p[chan]))
+ goto err_pwm_register;
+ pwm_set_drvdata(ap->p[chan], ap);
+ }
+
+ return 0;
+
+err_pwm_register:
+ while (--chan > 0)
+ pwm_unregister(ap->p[chan]);
+
+ iounmap(ap->iobase);
+err_ioremap:
+ clk_put(ap->clk);
+err_clk_get:
+ platform_set_drvdata(pdev, NULL);
+ kfree(ap);
+err_atmel_pwmc_alloc:
+ dev_dbg(&pdev->dev, "%s: error, returning %d\n", __func__, ret);
+ return ret;
+}
+
+static int __devexit atmel_pwmc_remove(struct platform_device *pdev)
+{
+ struct atmel_pwmc *ap = platform_get_drvdata(pdev);
+ int chan;
+
+ for (chan = 0; chan < NCHAN; chan++)
+ pwm_unregister(ap->p[chan]);
+
+ clk_enable(ap->clk);
+ pwmc_writel(ap, PWMC_IDR, -1);
+ pwmc_writel(ap, PWMC_DIS, -1);
+ clk_disable(ap->clk);
+
+ clk_put(ap->clk);
+ iounmap(ap->iobase);
+
+ kfree(ap);
+
+ return 0;
+}
+
+static struct platform_driver atmel_pwmc_driver = {
+ .driver = {
+ /* note: this name has to match the one in at91*_devices.c */
+ .name = "atmel_pwmc",
+ .owner = THIS_MODULE,
+ },
+ .probe = atmel_pwmc_probe,
+ .remove = __devexit_p(atmel_pwmc_remove),
+};
+
+static int __init atmel_pwmc_init(void)
+{
+ return platform_driver_register(&atmel_pwmc_driver);
+}
+module_init(atmel_pwmc_init);
+
+static void __exit atmel_pwmc_exit(void)
+{
+ platform_driver_unregister(&atmel_pwmc_driver);
+}
+module_exit(atmel_pwmc_exit);
+
+MODULE_AUTHOR("Bill Gatliff <bgat@billgatliff.com>");
+MODULE_DESCRIPTION("Driver for Atmel PWMC peripheral");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:atmel_pwmc");
--
1.7.2.3


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