blob: ea04abb3db8e1ebd4f3b355e18dacd7e6b1ec8d3 [file] [log] [blame]
* struct pwm_channel - driver handle to a PWM channel
* @regs: base of this channel's registers
* @index: number of this channel (0..31)
* @mck: base clock rate, which can be prescaled and maybe subdivided
* Drivers initialize a pwm_channel structure using pwm_channel_alloc().
* Then they configure its clock rate (derived from MCK), alignment,
* polarity, and duty cycle by writing directly to the channel registers,
* before enabling the channel by calling pwm_channel_enable().
* After emitting a PWM signal for the desired length of time, drivers
* may then pwm_channel_disable() or pwm_channel_free(). Both of these
* disable the channel, but when it's freed the IRQ is deconfigured and
* the channel must later be re-allocated and reconfigured.
* Note that if the period or duty cycle need to be changed while the
* PWM channel is operating, drivers must use the PWM_CUPD double buffer
* mechanism, either polling until they change or getting implicitly
* notified through a once-per-period interrupt handler.
struct pwm_channel {
void __iomem *regs;
unsigned index;
unsigned long mck;
extern int pwm_channel_alloc(int index, struct pwm_channel *ch);
extern int pwm_channel_free(struct pwm_channel *ch);
extern int pwm_clk_alloc(unsigned prescale, unsigned div);
extern void pwm_clk_free(unsigned clk);
extern int __pwm_channel_onoff(struct pwm_channel *ch, int enabled);
#define pwm_channel_enable(ch) __pwm_channel_onoff((ch), 1)
#define pwm_channel_disable(ch) __pwm_channel_onoff((ch), 0)
/* periodic interrupts, mostly for CUPD changes to period or cycle */
extern int pwm_channel_handler(struct pwm_channel *ch,
void (*handler)(struct pwm_channel *ch));
/* per-channel registers (banked at pwm_channel->regs) */
#define PWM_CMR 0x00 /* mode register */
#define PWM_CPR_CPD (1 << 10) /* set: CUPD modifies period */
#define PWM_CPR_CPOL (1 << 9) /* set: idle high */
#define PWM_CPR_CALG (1 << 8) /* set: center align */
#define PWM_CPR_CPRE (0xf << 0) /* mask: rate is mck/(2^pre) */
#define PWM_CPR_CLKA (0xb << 0) /* rate CLKA */
#define PWM_CPR_CLKB (0xc << 0) /* rate CLKB */
#define PWM_CDTY 0x04 /* duty cycle (max of CPRD) */
#define PWM_CPRD 0x08 /* period (count up from zero) */
#define PWM_CCNT 0x0c /* counter (20 bits?) */
#define PWM_CUPD 0x10 /* update CPRD (or CDTY) next period */
static inline void
pwm_channel_writel(struct pwm_channel *pwmc, unsigned offset, u32 val)
__raw_writel(val, pwmc->regs + offset);
static inline u32 pwm_channel_readl(struct pwm_channel *pwmc, unsigned offset)
return __raw_readl(pwmc->regs + offset);
#endif /* __LINUX_ATMEL_PWM_H */