arch/arm/cpu/armv7/tegra20/pwm.c

   1 /*
   2  * Tegra2 pulse width frequency modulator definitions
   3  *
   4  * Copyright (c) 2011 The Chromium OS Authors.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #include <common.h>
  10 #include <fdtdec.h>
  11 #include <asm/io.h>
  12 #include <asm/arch/clock.h>
  13 #include <asm/arch/pwm.h>
  14
  15 struct pwm_info {
  16         struct pwm_ctlr *pwm;           /* Registers for our pwm controller */
  17         int pwm_node;                   /* PWM device tree node */
  18 } local;
  19
  20 void pwm_enable(unsigned channel, int rate, int pulse_width, int freq_divider)
  21 {
  22         u32 reg;
  23
  24         assert(channel < PWM_NUM_CHANNELS);
  25
  26         /* TODO: Can we use clock_adjust_periph_pll_div() here? */
  27         clock_start_periph_pll(PERIPH_ID_PWM, CLOCK_ID_SFROM32KHZ, rate);
  28
  29         reg = PWM_ENABLE_MASK;
  30         reg |= pulse_width << PWM_WIDTH_SHIFT;
  31         reg |= freq_divider << PWM_DIVIDER_SHIFT;
  32         writel(reg, &local.pwm[channel].control);
  33         debug("%s: channel=%d, rate=%d\n", __func__, channel, rate);
  34 }
  35
  36 int pwm_request(const void *blob, int node, const char *prop_name)
  37 {
  38         int pwm_node;
  39         u32 data[3];
  40
  41         if (fdtdec_get_int_array(blob, node, prop_name, data,
  42                         ARRAY_SIZE(data))) {
  43                 debug("%s: Cannot decode PWM property '%s'\n", __func__,
  44                       prop_name);
  45                 return -1;
  46         }
  47
  48         pwm_node = fdt_node_offset_by_phandle(blob, data[0]);
  49         if (pwm_node != local.pwm_node) {
  50                 debug("%s: PWM property '%s' phandle %d not recognised"
  51                       "- expecting %d\n", __func__, prop_name, data[0],
  52                       local.pwm_node);
  53                 return -1;
  54         }
  55         if (data[1] >= PWM_NUM_CHANNELS) {
  56                 debug("%s: PWM property '%s': invalid channel %u\n", __func__,
  57                       prop_name, data[1]);
  58                 return -1;
  59         }
  60
  61         /*
  62          * TODO: We could maintain a list of requests, but it might not be
  63          * worth it for U-Boot.
  64          */
  65         return data[1];
  66 }
  67
  68 int pwm_init(const void *blob)
  69 {
  70         local.pwm_node = fdtdec_next_compatible(blob, 0,
  71                                                 COMPAT_NVIDIA_TEGRA20_PWM);
  72         if (local.pwm_node < 0) {
  73                 debug("%s: Cannot find device tree node\n", __func__);
  74                 return -1;
  75         }
  76
  77         local.pwm = (struct pwm_ctlr *)fdtdec_get_addr(blob, local.pwm_node,
  78                                                        "reg");
  79         if (local.pwm == (struct pwm_ctlr *)FDT_ADDR_T_NONE) {
  80                 debug("%s: Cannot find pwm reg address\n", __func__);
  81                 return -1;
  82         }
  83         debug("Tegra PWM at %p, node %d\n", local.pwm, local.pwm_node);
  84
  85         return 0;
  86 }