diff options
Diffstat (limited to 'arch/arm/plat-mxc/pwm.c')
| -rw-r--r-- | arch/arm/plat-mxc/pwm.c | 144 |
1 files changed, 62 insertions, 82 deletions
diff --git a/arch/arm/plat-mxc/pwm.c b/arch/arm/plat-mxc/pwm.c index 9bffbc507cc2..ae34198a79dd 100644 --- a/arch/arm/plat-mxc/pwm.c +++ b/arch/arm/plat-mxc/pwm.c @@ -15,65 +15,26 @@ #include <linux/clk.h> #include <linux/io.h> #include <linux/pwm.h> +#include <mach/hardware.h> + + +/* i.MX1 and i.MX21 share the same PWM function block: */ + +#define MX1_PWMC 0x00 /* PWM Control Register */ +#define MX1_PWMS 0x04 /* PWM Sample Register */ +#define MX1_PWMP 0x08 /* PWM Period Register */ + + +/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */ + +#define MX3_PWMCR 0x00 /* PWM Control Register */ +#define MX3_PWMSAR 0x0C /* PWM Sample Register */ +#define MX3_PWMPR 0x10 /* PWM Period Register */ +#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4) +#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) +#define MX3_PWMCR_EN (1 << 0) + -#if defined CONFIG_ARCH_MX1 || defined CONFIG_ARCH_MX21 -#define PWM_VER_1 - -#define PWMCR 0x00 /* PWM Control Register */ -#define PWMSR 0x04 /* PWM Sample Register */ -#define PWMPR 0x08 /* PWM Period Register */ -#define PWMCNR 0x0C /* PWM Counter Register */ - -#define PWMCR_HCTR (1 << 18) /* Halfword FIFO Data Swapping */ -#define PWMCR_BCTR (1 << 17) /* Byte FIFO Data Swapping */ -#define PWMCR_SWR (1 << 16) /* Software Reset */ -#define PWMCR_CLKSRC_PERCLK (0 << 15) /* PERCLK Clock Source */ -#define PWMCR_CLKSRC_CLK32 (1 << 15) /* 32KHz Clock Source */ -#define PWMCR_PRESCALER(x) (((x - 1) & 0x7F) << 8) /* PRESCALER */ -#define PWMCR_IRQ (1 << 7) /* Interrupt Request */ -#define PWMCR_IRQEN (1 << 6) /* Interrupt Request Enable */ -#define PWMCR_FIFOAV (1 << 5) /* FIFO Available */ -#define PWMCR_EN (1 << 4) /* Enables/Disables the PWM */ -#define PWMCR_REPEAT(x) (((x) & 0x03) << 2) /* Sample Repeats */ -#define PWMCR_DIV(x) (((x) & 0x03) << 0) /* Clock divider 2/4/8/16 */ - -#define MAX_DIV (128 * 16) -#endif - -#if defined CONFIG_MACH_MX27 || defined CONFIG_ARCH_MX31 -#define PWM_VER_2 - -#define PWMCR 0x00 /* PWM Control Register */ -#define PWMSR 0x04 /* PWM Status Register */ -#define PWMIR 0x08 /* PWM Interrupt Register */ -#define PWMSAR 0x0C /* PWM Sample Register */ -#define PWMPR 0x10 /* PWM Period Register */ -#define PWMCNR 0x14 /* PWM Counter Register */ - -#define PWMCR_EN (1 << 0) /* Enables/Disables the PWM */ -#define PWMCR_REPEAT(x) (((x) & 0x03) << 1) /* Sample Repeats */ -#define PWMCR_SWR (1 << 3) /* Software Reset */ -#define PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)/* PRESCALER */ -#define PWMCR_CLKSRC(x) (((x) & 0x3) << 16) -#define PWMCR_CLKSRC_OFF (0 << 16) -#define PWMCR_CLKSRC_IPG (1 << 16) -#define PWMCR_CLKSRC_IPG_HIGH (2 << 16) -#define PWMCR_CLKSRC_CLK32 (3 << 16) -#define PWMCR_POUTC -#define PWMCR_HCTR (1 << 20) /* Halfword FIFO Data Swapping */ -#define PWMCR_BCTR (1 << 21) /* Byte FIFO Data Swapping */ -#define PWMCR_DBGEN (1 << 22) /* Debug Mode */ -#define PWMCR_WAITEN (1 << 23) /* Wait Mode */ -#define PWMCR_DOZEN (1 << 24) /* Doze Mode */ -#define PWMCR_STOPEN (1 << 25) /* Stop Mode */ -#define PWMCR_FWM(x) (((x) & 0x3) << 26) /* FIFO Water Mark */ - -#define MAX_DIV 4096 -#endif - -#define PWMS_SAMPLE(x) ((x) & 0xFFFF) /* Contains a two-sample word */ -#define PWMP_PERIOD(x) ((x) & 0xFFFF) /* Represents the PWM's period */ -#define PWMC_COUNTER(x) ((x) & 0xFFFF) /* Represents the current count value */ struct pwm_device { struct list_head node; @@ -91,32 +52,52 @@ struct pwm_device { int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) { - unsigned long long c; - unsigned long period_cycles, duty_cycles, prescale; - if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) return -EINVAL; - c = clk_get_rate(pwm->clk); - c = c * period_ns; - do_div(c, 1000000000); - period_cycles = c; - - prescale = period_cycles / 0x10000 + 1; - - period_cycles /= prescale; - c = (unsigned long long)period_cycles * duty_ns; - do_div(c, period_ns); - duty_cycles = c; - -#ifdef PWM_VER_2 - writel(duty_cycles, pwm->mmio_base + PWMSAR); - writel(period_cycles, pwm->mmio_base + PWMPR); - writel(PWMCR_PRESCALER(prescale - 1) | PWMCR_CLKSRC_IPG_HIGH | PWMCR_EN, - pwm->mmio_base + PWMCR); -#elif defined PWM_VER_1 -#error PWM not yet working on MX1 / MX21 -#endif + if (cpu_is_mx27() || cpu_is_mx3()) { + unsigned long long c; + unsigned long period_cycles, duty_cycles, prescale; + c = clk_get_rate(pwm->clk); + c = c * period_ns; + do_div(c, 1000000000); + period_cycles = c; + + prescale = period_cycles / 0x10000 + 1; + + period_cycles /= prescale; + c = (unsigned long long)period_cycles * duty_ns; + do_div(c, period_ns); + duty_cycles = c; + + writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR); + writel(period_cycles, pwm->mmio_base + MX3_PWMPR); + writel(MX3_PWMCR_PRESCALER(prescale - 1) | + MX3_PWMCR_CLKSRC_IPG_HIGH | MX3_PWMCR_EN, + pwm->mmio_base + MX3_PWMCR); + } else if (cpu_is_mx1() || cpu_is_mx21()) { + /* The PWM subsystem allows for exact frequencies. However, + * I cannot connect a scope on my device to the PWM line and + * thus cannot provide the program the PWM controller + * exactly. Instead, I'm relying on the fact that the + * Bootloader (u-boot or WinCE+haret) has programmed the PWM + * function group already. So I'll just modify the PWM sample + * register to follow the ratio of duty_ns vs. period_ns + * accordingly. + * + * This is good enought for programming the brightness of + * the LCD backlight. + * + * The real implementation would divide PERCLK[0] first by + * both the prescaler (/1 .. /128) and then by CLKSEL + * (/2 .. /16). + */ + u32 max = readl(pwm->mmio_base + MX1_PWMP); + u32 p = max * duty_ns / period_ns; + writel(max - p, pwm->mmio_base + MX1_PWMS); + } else { + BUG(); + } return 0; } @@ -297,4 +278,3 @@ module_exit(mxc_pwm_exit); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); - |