diff options
Diffstat (limited to 'include/linux/atmel_pwm.h')
| -rw-r--r-- | include/linux/atmel_pwm.h | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/include/linux/atmel_pwm.h b/include/linux/atmel_pwm.h new file mode 100644 index 000000000000..ea04abb3db8e --- /dev/null +++ b/include/linux/atmel_pwm.h @@ -0,0 +1,70 @@ +#ifndef __LINUX_ATMEL_PWM_H +#define __LINUX_ATMEL_PWM_H + +/** + * 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 */ |