#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");
