Lars-Peter Clausen
14 years ago
parent
498bf7402a
commit
e438c665db
@ -0,0 +1,137 @@
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diff --git a/arch/arm/plat-mxc/pwm.c b/arch/arm/plat-mxc/pwm.c
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index c36f263..acc5dc1 100644
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--- a/arch/arm/plat-mxc/pwm.c
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+++ b/arch/arm/plat-mxc/pwm.c
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@@ -25,6 +25,11 @@
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#define MX1_PWMS 0x04 /* PWM Sample Register */
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#define MX1_PWMP 0x08 /* PWM Period Register */
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+#define MX1_PWMC_EN (1 << 4)
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+#define MX1_PWMC_PRESCALER_MASK (0x7f << 8)
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+#define MX1_PWMC_PRESCALER(x) ((x & 0x7f) << 8)
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+#define MX1_PWMC_CLKSEL_MASK 0x3
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+#define MX1_PWMC_CLKSEL(x) ((x & 0x3))
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/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
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@@ -54,25 +59,32 @@ struct pwm_device {
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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+ unsigned long long c;
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+ unsigned long period_cycles, duty_cycles, prescale;
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+
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if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
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return -EINVAL;
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- if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
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- unsigned long long c;
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- unsigned long period_cycles, duty_cycles, prescale;
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- u32 cr;
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+ c = clk_get_rate(pwm->clk);
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+
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+ c = c * period_ns;
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+
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+ if (cpu_is_mx1() || cpu_is_mx2())
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+ c >>= 1;
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- c = clk_get_rate(pwm->clk);
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- c = c * period_ns;
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- do_div(c, 1000000000);
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- period_cycles = c;
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+ do_div(c, 1000000000);
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+ period_cycles = c;
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- prescale = period_cycles / 0x10000 + 1;
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+ prescale = period_cycles / 0x10000 + 1;
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- period_cycles /= prescale;
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- c = (unsigned long long)period_cycles * duty_ns;
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- do_div(c, period_ns);
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- duty_cycles = c;
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+ period_cycles /= prescale;
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+ c = (unsigned long long)period_cycles * duty_ns;
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+ do_div(c, period_ns);
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+ duty_cycles = c;
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+
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+
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+ if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
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+ u32 cr;
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writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
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writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
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@@ -86,25 +98,28 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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writel(cr, pwm->mmio_base + MX3_PWMCR);
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} else if (cpu_is_mx1() || cpu_is_mx21()) {
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- /* The PWM subsystem allows for exact frequencies. However,
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- * I cannot connect a scope on my device to the PWM line and
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- * thus cannot provide the program the PWM controller
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- * exactly. Instead, I'm relying on the fact that the
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- * Bootloader (u-boot or WinCE+haret) has programmed the PWM
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- * function group already. So I'll just modify the PWM sample
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- * register to follow the ratio of duty_ns vs. period_ns
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- * accordingly.
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- *
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- * This is good enough for programming the brightness of
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- * the LCD backlight.
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- *
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- * The real implementation would divide PERCLK[0] first by
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- * both the prescaler (/1 .. /128) and then by CLKSEL
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- * (/2 .. /16).
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- */
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- u32 max = readl(pwm->mmio_base + MX1_PWMP);
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- u32 p = max * duty_ns / period_ns;
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- writel(max - p, pwm->mmio_base + MX1_PWMS);
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+ unsigned long clksel = 0;
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+ u32 ctrl;
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+
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+ while (prescale >= 0x80 && clksel < 4) {
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+ prescale >>= 1;
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+ ++clksel;
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+ }
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+
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+ if (clksel > 3)
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+ return -EINVAL;
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+
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+ ctrl = readl(pwm->mmio_base + MX1_PWMC);
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+ writel(ctrl & ~MX1_PWMC_EN, pwm->mmio_base + MX1_PWMC);
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+
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+ writel(duty_cycles, pwm->mmio_base + MX1_PWMS);
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+ writel(period_cycles, pwm->mmio_base + MX1_PWMP);
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+
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+ ctrl &= ~(MX1_PWMC_PRESCALER_MASK | MX1_PWMC_CLKSEL_MASK);
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+ ctrl |= MX1_PWMC_PRESCALER(prescale);
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+ ctrl |= MX1_PWMC_CLKSEL(clksel);
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+ writel(ctrl, pwm->mmio_base + MX1_PWMC);
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+
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} else {
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BUG();
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}
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@@ -116,6 +130,11 @@ EXPORT_SYMBOL(pwm_config);
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int pwm_enable(struct pwm_device *pwm)
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{
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int rc = 0;
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+ if (cpu_is_mx1() || cpu_is_mx2()) {
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+ u32 ctrl;
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+ ctrl = readl(pwm->mmio_base + MX1_PWMC);
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+ writel(ctrl | MX1_PWMC_EN, pwm->mmio_base + MX1_PWMC);
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+ }
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if (!pwm->clk_enabled) {
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rc = clk_enable(pwm->clk);
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@@ -128,7 +147,13 @@ EXPORT_SYMBOL(pwm_enable);
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void pwm_disable(struct pwm_device *pwm)
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{
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- writel(0, pwm->mmio_base + MX3_PWMCR);
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+ if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
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+ writel(0, pwm->mmio_base + MX3_PWMCR);
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+ } else if (cpu_is_mx1() || cpu_is_mx2()) {
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+ u32 ctrl;
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+ ctrl = readl(pwm->mmio_base + MX1_PWMC);
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+ writel(ctrl & ~MX1_PWMC_EN, pwm->mmio_base + MX1_PWMC);
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+ }
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if (pwm->clk_enabled) {
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clk_disable(pwm->clk);
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