Basic PWM driver for AVR32 and AT91
PWM device setup, and a simple PWM driver exposing a programming interface
giving access to each channel's full capabilities. Note that this doesn't
support starting several channels in synch.
[hskinnemoen@atmel.com: allocate platform device dynamically]
[hskinnemoen@atmel.com: Kconfig fix]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/misc/atmel_pwm.c b/drivers/misc/atmel_pwm.c
new file mode 100644
index 0000000..f8d3b9a
--- /dev/null
+++ b/drivers/misc/atmel_pwm.c
@@ -0,0 +1,409 @@
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/atmel_pwm.h>
+
+
+/*
+ * This is a simple driver for the PWM controller found in various newer
+ * Atmel SOCs, including the AVR32 series and the AT91sam9263.
+ *
+ * Chips with current Linux ports have only 4 PWM channels, out of max 32.
+ * AT32UC3A and AT32UC3B chips have 7 channels (but currently no Linux).
+ * Docs are inconsistent about the width of the channel counter registers;
+ * it's at least 16 bits, but several places say 20 bits.
+ */
+#define PWM_NCHAN 4 /* max 32 */
+
+struct pwm {
+ spinlock_t lock;
+ struct platform_device *pdev;
+ u32 mask;
+ int irq;
+ void __iomem *base;
+ struct clk *clk;
+ struct pwm_channel *channel[PWM_NCHAN];
+ void (*handler[PWM_NCHAN])(struct pwm_channel *);
+};
+
+
+/* global PWM controller registers */
+#define PWM_MR 0x00
+#define PWM_ENA 0x04
+#define PWM_DIS 0x08
+#define PWM_SR 0x0c
+#define PWM_IER 0x10
+#define PWM_IDR 0x14
+#define PWM_IMR 0x18
+#define PWM_ISR 0x1c
+
+static inline void pwm_writel(const struct pwm *p, unsigned offset, u32 val)
+{
+ __raw_writel(val, p->base + offset);
+}
+
+static inline u32 pwm_readl(const struct pwm *p, unsigned offset)
+{
+ return __raw_readl(p->base + offset);
+}
+
+static inline void __iomem *pwmc_regs(const struct pwm *p, int index)
+{
+ return p->base + 0x200 + index * 0x20;
+}
+
+static struct pwm *pwm;
+
+static void pwm_dumpregs(struct pwm_channel *ch, char *tag)
+{
+ struct device *dev = &pwm->pdev->dev;
+
+ dev_dbg(dev, "%s: mr %08x, sr %08x, imr %08x\n",
+ tag,
+ pwm_readl(pwm, PWM_MR),
+ pwm_readl(pwm, PWM_SR),
+ pwm_readl(pwm, PWM_IMR));
+ dev_dbg(dev,
+ "pwm ch%d - mr %08x, dty %u, prd %u, cnt %u\n",
+ ch->index,
+ pwm_channel_readl(ch, PWM_CMR),
+ pwm_channel_readl(ch, PWM_CDTY),
+ pwm_channel_readl(ch, PWM_CPRD),
+ pwm_channel_readl(ch, PWM_CCNT));
+}
+
+
+/**
+ * pwm_channel_alloc - allocate an unused PWM channel
+ * @index: identifies the channel
+ * @ch: structure to be initialized
+ *
+ * Drivers allocate PWM channels according to the board's wiring, and
+ * matching board-specific setup code. Returns zero or negative errno.
+ */
+int pwm_channel_alloc(int index, struct pwm_channel *ch)
+{
+ unsigned long flags;
+ int status = 0;
+
+ /* insist on PWM init, with this signal pinned out */
+ if (!pwm || !(pwm->mask & 1 << index))
+ return -ENODEV;
+
+ if (index < 0 || index >= PWM_NCHAN || !ch)
+ return -EINVAL;
+ memset(ch, 0, sizeof *ch);
+
+ spin_lock_irqsave(&pwm->lock, flags);
+ if (pwm->channel[index])
+ status = -EBUSY;
+ else {
+ clk_enable(pwm->clk);
+
+ ch->regs = pwmc_regs(pwm, index);
+ ch->index = index;
+
+ /* REVISIT: ap7000 seems to go 2x as fast as we expect!! */
+ ch->mck = clk_get_rate(pwm->clk);
+
+ pwm->channel[index] = ch;
+ pwm->handler[index] = NULL;
+
+ /* channel and irq are always disabled when we return */
+ pwm_writel(pwm, PWM_DIS, 1 << index);
+ pwm_writel(pwm, PWM_IDR, 1 << index);
+ }
+ spin_unlock_irqrestore(&pwm->lock, flags);
+ return status;
+}
+EXPORT_SYMBOL(pwm_channel_alloc);
+
+static int pwmcheck(struct pwm_channel *ch)
+{
+ int index;
+
+ if (!pwm)
+ return -ENODEV;
+ if (!ch)
+ return -EINVAL;
+ index = ch->index;
+ if (index < 0 || index >= PWM_NCHAN || pwm->channel[index] != ch)
+ return -EINVAL;
+
+ return index;
+}
+
+/**
+ * pwm_channel_free - release a previously allocated channel
+ * @ch: the channel being released
+ *
+ * The channel is completely shut down (counter and IRQ disabled),
+ * and made available for re-use. Returns zero, or negative errno.
+ */
+int pwm_channel_free(struct pwm_channel *ch)
+{
+ unsigned long flags;
+ int t;
+
+ spin_lock_irqsave(&pwm->lock, flags);
+ t = pwmcheck(ch);
+ if (t >= 0) {
+ pwm->channel[t] = NULL;
+ pwm->handler[t] = NULL;
+
+ /* channel and irq are always disabled when we return */
+ pwm_writel(pwm, PWM_DIS, 1 << t);
+ pwm_writel(pwm, PWM_IDR, 1 << t);
+
+ clk_disable(pwm->clk);
+ t = 0;
+ }
+ spin_unlock_irqrestore(&pwm->lock, flags);
+ return t;
+}
+EXPORT_SYMBOL(pwm_channel_free);
+
+int __pwm_channel_onoff(struct pwm_channel *ch, int enabled)
+{
+ unsigned long flags;
+ int t;
+
+ /* OMITTED FUNCTIONALITY: starting several channels in synch */
+
+ spin_lock_irqsave(&pwm->lock, flags);
+ t = pwmcheck(ch);
+ if (t >= 0) {
+ pwm_writel(pwm, enabled ? PWM_ENA : PWM_DIS, 1 << t);
+ t = 0;
+ pwm_dumpregs(ch, enabled ? "enable" : "disable");
+ }
+ spin_unlock_irqrestore(&pwm->lock, flags);
+
+ return t;
+}
+EXPORT_SYMBOL(__pwm_channel_onoff);
+
+/**
+ * pwm_clk_alloc - allocate and configure CLKA or CLKB
+ * @prescale: from 0..10, the power of two used to divide MCK
+ * @div: from 1..255, the linear divisor to use
+ *
+ * Returns PWM_CPR_CLKA, PWM_CPR_CLKB, or negative errno. The allocated
+ * clock will run with a period of (2^prescale * div) / MCK, or twice as
+ * long if center aligned PWM output is used. The clock must later be
+ * deconfigured using pwm_clk_free().
+ */
+int pwm_clk_alloc(unsigned prescale, unsigned div)
+{
+ unsigned long flags;
+ u32 mr;
+ u32 val = (prescale << 8) | div;
+ int ret = -EBUSY;
+
+ if (prescale >= 10 || div == 0 || div > 255)
+ return -EINVAL;
+
+ spin_lock_irqsave(&pwm->lock, flags);
+ mr = pwm_readl(pwm, PWM_MR);
+ if ((mr & 0xffff) == 0) {
+ mr |= val;
+ ret = PWM_CPR_CLKA;
+ }
+ if ((mr & (0xffff << 16)) == 0) {
+ mr |= val << 16;
+ ret = PWM_CPR_CLKB;
+ }
+ if (ret > 0)
+ pwm_writel(pwm, PWM_MR, mr);
+ spin_unlock_irqrestore(&pwm->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(pwm_clk_alloc);
+
+/**
+ * pwm_clk_free - deconfigure and release CLKA or CLKB
+ *
+ * Reverses the effect of pwm_clk_alloc().
+ */
+void pwm_clk_free(unsigned clk)
+{
+ unsigned long flags;
+ u32 mr;
+
+ spin_lock_irqsave(&pwm->lock, flags);
+ mr = pwm_readl(pwm, PWM_MR);
+ if (clk == PWM_CPR_CLKA)
+ pwm_writel(pwm, PWM_MR, mr & ~(0xffff << 0));
+ if (clk == PWM_CPR_CLKB)
+ pwm_writel(pwm, PWM_MR, mr & ~(0xffff << 16));
+ spin_unlock_irqrestore(&pwm->lock, flags);
+}
+EXPORT_SYMBOL(pwm_clk_free);
+
+/**
+ * pwm_channel_handler - manage channel's IRQ handler
+ * @ch: the channel
+ * @handler: the handler to use, possibly NULL
+ *
+ * If the handler is non-null, the handler will be called after every
+ * period of this PWM channel. If the handler is null, this channel
+ * won't generate an IRQ.
+ */
+int pwm_channel_handler(struct pwm_channel *ch,
+ void (*handler)(struct pwm_channel *ch))
+{
+ unsigned long flags;
+ int t;
+
+ spin_lock_irqsave(&pwm->lock, flags);
+ t = pwmcheck(ch);
+ if (t >= 0) {
+ pwm->handler[t] = handler;
+ pwm_writel(pwm, handler ? PWM_IER : PWM_IDR, 1 << t);
+ t = 0;
+ }
+ spin_unlock_irqrestore(&pwm->lock, flags);
+
+ return t;
+}
+EXPORT_SYMBOL(pwm_channel_handler);
+
+static irqreturn_t pwm_irq(int id, void *_pwm)
+{
+ struct pwm *p = _pwm;
+ irqreturn_t handled = IRQ_NONE;
+ u32 irqstat;
+ int index;
+
+ spin_lock(&p->lock);
+
+ /* ack irqs, then handle them */
+ irqstat = pwm_readl(pwm, PWM_ISR);
+
+ while (irqstat) {
+ struct pwm_channel *ch;
+ void (*handler)(struct pwm_channel *ch);
+
+ index = ffs(irqstat) - 1;
+ irqstat &= ~(1 << index);
+ ch = pwm->channel[index];
+ handler = pwm->handler[index];
+ if (handler && ch) {
+ spin_unlock(&p->lock);
+ handler(ch);
+ spin_lock(&p->lock);
+ handled = IRQ_HANDLED;
+ }
+ }
+
+ spin_unlock(&p->lock);
+ return handled;
+}
+
+static int __init pwm_probe(struct platform_device *pdev)
+{
+ struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ int irq = platform_get_irq(pdev, 0);
+ u32 *mp = pdev->dev.platform_data;
+ struct pwm *p;
+ int status = -EIO;
+
+ if (pwm)
+ return -EBUSY;
+ if (!r || irq < 0 || !mp || !*mp)
+ return -ENODEV;
+ if (*mp & ~((1<<PWM_NCHAN)-1)) {
+ dev_warn(&pdev->dev, "mask 0x%x ... more than %d channels\n",
+ *mp, PWM_NCHAN);
+ return -EINVAL;
+ }
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ spin_lock_init(&p->lock);
+ p->pdev = pdev;
+ p->mask = *mp;
+ p->irq = irq;
+ p->base = ioremap(r->start, r->end - r->start + 1);
+ if (!p->base)
+ goto fail;
+ p->clk = clk_get(&pdev->dev, "mck");
+ if (IS_ERR(p->clk)) {
+ status = PTR_ERR(p->clk);
+ p->clk = NULL;
+ goto fail;
+ }
+
+ status = request_irq(irq, pwm_irq, 0, pdev->name, p);
+ if (status < 0)
+ goto fail;
+
+ pwm = p;
+ platform_set_drvdata(pdev, p);
+
+ return 0;
+
+fail:
+ if (p->clk)
+ clk_put(p->clk);
+ if (p->base)
+ iounmap(p->base);
+
+ kfree(p);
+ return status;
+}
+
+static int __exit pwm_remove(struct platform_device *pdev)
+{
+ struct pwm *p = platform_get_drvdata(pdev);
+
+ if (p != pwm)
+ return -EINVAL;
+
+ clk_enable(pwm->clk);
+ pwm_writel(pwm, PWM_DIS, (1 << PWM_NCHAN) - 1);
+ pwm_writel(pwm, PWM_IDR, (1 << PWM_NCHAN) - 1);
+ clk_disable(pwm->clk);
+
+ pwm = NULL;
+
+ free_irq(p->irq, p);
+ clk_put(p->clk);
+ iounmap(p->base);
+ kfree(p);
+
+ return 0;
+}
+
+static struct platform_driver atmel_pwm_driver = {
+ .driver = {
+ .name = "atmel_pwm",
+ .owner = THIS_MODULE,
+ },
+ .remove = __exit_p(pwm_remove),
+
+ /* NOTE: PWM can keep running in AVR32 "idle" and "frozen" states;
+ * and all AT91sam9263 states, albeit at reduced clock rate if
+ * MCK becomes the slow clock (i.e. what Linux labels STR).
+ */
+};
+
+static int __init pwm_init(void)
+{
+ return platform_driver_probe(&atmel_pwm_driver, pwm_probe);
+}
+module_init(pwm_init);
+
+static void __exit pwm_exit(void)
+{
+ platform_driver_unregister(&atmel_pwm_driver);
+}
+module_exit(pwm_exit);
+
+MODULE_DESCRIPTION("Driver for AT32/AT91 PWM module");
+MODULE_LICENSE("GPL");