diff options
Diffstat (limited to 'drivers/misc')
| -rw-r--r-- | drivers/misc/Kconfig | 9 | ||||
| -rw-r--r-- | drivers/misc/Makefile | 1 | ||||
| -rw-r--r-- | drivers/misc/atmel_pwm.c | 409 |
3 files changed, 419 insertions, 0 deletions
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 7b5220ca7d7f..1941587a7aa2 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -13,6 +13,15 @@ menuconfig MISC_DEVICES if MISC_DEVICES +config ATMEL_PWM + tristate "Atmel AT32/AT91 PWM support" + depends on AVR32 || ARCH_AT91 + help + This option enables device driver support for the PWM channels + on certain Atmel prcoessors. Pulse Width Modulation is used for + purposes including software controlled power-efficent backlights + on LCD displays, motor control, and waveform generation. + config IBM_ASM tristate "Device driver for IBM RSA service processor" depends on X86 && PCI && INPUT && EXPERIMENTAL diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 7f13549cc87e..3b12f5da8562 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_HDPU_FEATURES) += hdpuftrs/ obj-$(CONFIG_MSI_LAPTOP) += msi-laptop.o obj-$(CONFIG_ACER_WMI) += acer-wmi.o obj-$(CONFIG_ASUS_LAPTOP) += asus-laptop.o +obj-$(CONFIG_ATMEL_PWM) += atmel_pwm.o obj-$(CONFIG_ATMEL_SSC) += atmel-ssc.o obj-$(CONFIG_TC1100_WMI) += tc1100-wmi.o obj-$(CONFIG_LKDTM) += lkdtm.o diff --git a/drivers/misc/atmel_pwm.c b/drivers/misc/atmel_pwm.c new file mode 100644 index 000000000000..f8d3b9a76cbd --- /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"); |