#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; } else 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, "pwm_clk"); 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"); MODULE_ALIAS("platform:atmel_pwm");