target/linux/imx21/patches/040-pwm.patch

   1 --- a/arch/arm/plat-mxc/pwm.c
   2 +++ b/arch/arm/plat-mxc/pwm.c
   3 @@ -25,6 +25,11 @@
   4  #define MX1_PWMS    0x04   /* PWM Sample Register */
   5  #define MX1_PWMP    0x08   /* PWM Period Register */
   6
   7 +#define MX1_PWMC_EN (1 << 4)
   8 +#define MX1_PWMC_PRESCALER_MASK (0x7f << 8)
   9 +#define MX1_PWMC_PRESCALER(x) ((x & 0x7f) << 8)
  10 +#define MX1_PWMC_CLKSEL_MASK 0x3
  11 +#define MX1_PWMC_CLKSEL(x) ((x & 0x3))
  12
  13  /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
  14
  15 @@ -54,26 +59,33 @@ struct pwm_device {
  16
  17  int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  18  {
  19 +       unsigned long long c;
  20 +       unsigned long period_cycles, duty_cycles, prescale;
  21 +
  22         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
  23                 return -EINVAL;
  24
  25 +       c = clk_get_rate(pwm->clk);
  26 +
  27 +       c = c * period_ns;
  28 +
  29 +       if (cpu_is_mx1() || cpu_is_mx2())
  30 +               c >>= 1;
  31 +
  32 +       do_div(c, 1000000000);
  33 +       period_cycles = c;
  34 +
  35 +       prescale = period_cycles / 0x10000 + 1;
  36 +
  37 +       period_cycles /= prescale;
  38 +       c = (unsigned long long)period_cycles * duty_ns;
  39 +       do_div(c, period_ns);
  40 +       duty_cycles = c;
  41 +
  42 +
  43         if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
  44 -               unsigned long long c;
  45 -               unsigned long period_cycles, duty_cycles, prescale;
  46                 u32 cr;
  47
  48 -               c = clk_get_rate(pwm->clk);
  49 -               c = c * period_ns;
  50 -               do_div(c, 1000000000);
  51 -               period_cycles = c;
  52 -
  53 -               prescale = period_cycles / 0x10000 + 1;
  54 -
  55 -               period_cycles /= prescale;
  56 -               c = (unsigned long long)period_cycles * duty_ns;
  57 -               do_div(c, period_ns);
  58 -               duty_cycles = c;
  59 -
  60                 writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
  61                 writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
  62
  63 @@ -86,25 +98,28 @@ int pwm_config(struct pwm_device *pwm, i
  64
  65                 writel(cr, pwm->mmio_base + MX3_PWMCR);
  66         } else if (cpu_is_mx1() || cpu_is_mx21()) {
  67 -               /* The PWM subsystem allows for exact frequencies. However,
  68 -                * I cannot connect a scope on my device to the PWM line and
  69 -                * thus cannot provide the program the PWM controller
  70 -                * exactly. Instead, I'm relying on the fact that the
  71 -                * Bootloader (u-boot or WinCE+haret) has programmed the PWM
  72 -                * function group already. So I'll just modify the PWM sample
  73 -                * register to follow the ratio of duty_ns vs. period_ns
  74 -                * accordingly.
  75 -                *
  76 -                * This is good enough for programming the brightness of
  77 -                * the LCD backlight.
  78 -                *
  79 -                * The real implementation would divide PERCLK[0] first by
  80 -                * both the prescaler (/1 .. /128) and then by CLKSEL
  81 -                * (/2 .. /16).
  82 -                */
  83 -               u32 max = readl(pwm->mmio_base + MX1_PWMP);
  84 -               u32 p = max * duty_ns / period_ns;
  85 -               writel(max - p, pwm->mmio_base + MX1_PWMS);
  86 +               unsigned long clksel = 0;
  87 +               u32 ctrl;
  88 +
  89 +               while (prescale >= 0x80 && clksel < 4) {
  90 +                       prescale >>= 1;
  91 +                       ++clksel;
  92 +               }
  93 +
  94 +               if (clksel > 3)
  95 +                       return -EINVAL;
  96 +
  97 +               ctrl = readl(pwm->mmio_base + MX1_PWMC);
  98 +               writel(ctrl & ~MX1_PWMC_EN, pwm->mmio_base + MX1_PWMC);
  99 +
 100 +               writel(duty_cycles, pwm->mmio_base + MX1_PWMS);
 101 +               writel(period_cycles, pwm->mmio_base + MX1_PWMP);
 102 +
 103 +               ctrl &= ~(MX1_PWMC_PRESCALER_MASK | MX1_PWMC_CLKSEL_MASK);
 104 +               ctrl |= MX1_PWMC_PRESCALER(prescale);
 105 +               ctrl |= MX1_PWMC_CLKSEL(clksel);
 106 +               writel(ctrl, pwm->mmio_base + MX1_PWMC);
 107 +
 108         } else {
 109                 BUG();
 110         }
 111 @@ -116,6 +131,11 @@ EXPORT_SYMBOL(pwm_config);
 112  int pwm_enable(struct pwm_device *pwm)
 113  {
 114         int rc = 0;
 115 +       if (cpu_is_mx1() || cpu_is_mx2()) {
 116 +               u32 ctrl;
 117 +               ctrl = readl(pwm->mmio_base + MX1_PWMC);
 118 +               writel(ctrl | MX1_PWMC_EN, pwm->mmio_base + MX1_PWMC);
 119 +       }
 120
 121         if (!pwm->clk_enabled) {
 122                 rc = clk_enable(pwm->clk);
 123 @@ -128,7 +148,13 @@ EXPORT_SYMBOL(pwm_enable);
 124
 125  void pwm_disable(struct pwm_device *pwm)
 126  {
 127 -       writel(0, pwm->mmio_base + MX3_PWMCR);
 128 +       if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
 129 +               writel(0, pwm->mmio_base + MX3_PWMCR);
 130 +       } else if (cpu_is_mx1() || cpu_is_mx2()) {
 131 +               u32 ctrl;
 132 +               ctrl = readl(pwm->mmio_base + MX1_PWMC);
 133 +               writel(ctrl & ~MX1_PWMC_EN, pwm->mmio_base + MX1_PWMC);
 134 +       }
 135
 136         if (pwm->clk_enabled) {
 137                 clk_disable(pwm->clk);