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Commit 9a1e8eb1 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
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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: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarHaavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8cece84

arch/avr32/mach-at32ap/at32ap700x.c

+54 −0
Original line number Diff line number Diff line
@@ -1185,6 +1185,59 @@ at32_add_device_lcdc(unsigned int id, struct atmel_lcdfb_info *data, 
}

#endif



/* --------------------------------------------------------------------

 *  PWM

 * -------------------------------------------------------------------- */

static struct resource atmel_pwm0_resource[] __initdata = {

	PBMEM(0xfff01400),

	IRQ(24),

};

static struct clk atmel_pwm0_mck = {

	.name		= "mck",

	.parent		= &pbb_clk,

	.mode		= pbb_clk_mode,

	.get_rate	= pbb_clk_get_rate,

	.index		= 5,

};



struct platform_device *__init at32_add_device_pwm(u32 mask)

{

	struct platform_device *pdev;



	if (!mask)

		return NULL;



	pdev = platform_device_alloc("atmel_pwm", 0);

	if (!pdev)

		return NULL;



	if (platform_device_add_resources(pdev, atmel_pwm0_resource,

				ARRAY_SIZE(atmel_pwm0_resource)))

		goto out_free_pdev;



	if (platform_device_add_data(pdev, &mask, sizeof(mask)))

		goto out_free_pdev;



	if (mask & (1 << 0))

		select_peripheral(PA(28), PERIPH_A, 0);

	if (mask & (1 << 1))

		select_peripheral(PA(29), PERIPH_A, 0);

	if (mask & (1 << 2))

		select_peripheral(PA(21), PERIPH_B, 0);

	if (mask & (1 << 3))

		select_peripheral(PA(22), PERIPH_B, 0);



	atmel_pwm0_mck.dev = &pdev->dev;



	platform_device_add(pdev);



	return pdev;



out_free_pdev:

	platform_device_put(pdev);

	return NULL;

}



/* --------------------------------------------------------------------

 *  SSC

 * -------------------------------------------------------------------- */
@@ -1646,6 +1699,7 @@ struct clk *at32_clock_list[] = { 
	&atmel_usart1_usart,

	&atmel_usart2_usart,

	&atmel_usart3_usart,

	&atmel_pwm0_mck,

#if defined(CONFIG_CPU_AT32AP7000)

	&macb0_hclk,

	&macb0_pclk,

drivers/misc/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -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

drivers/misc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/misc/atmel_pwm.c

0 → 100644
+409 −0
Original line number Diff line number Diff line 
#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");

include/asm-avr32/arch-at32ap/board.h

+3 −0
Original line number Diff line number Diff line
@@ -51,6 +51,9 @@ struct platform_device * 
at32_add_device_ide(unsigned int id, unsigned int extint,

		    struct ide_platform_data *data);



/* mask says which PWM channels to mux */

struct platform_device *at32_add_device_pwm(u32 mask);



/* depending on what's hooked up, not all SSC pins will be used */

#define	ATMEL_SSC_TK		0x01

#define	ATMEL_SSC_TF		0x02