git.sur5r.net Git - u-boot/blob - arch/arm/mach-tegra/pwm.c

   1 /*
   2  * Tegra 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         if (rate) {
  28                 clock_start_periph_pll(PERIPH_ID_PWM, CLOCK_ID_SFROM32KHZ,
  29                                        rate);
  30         }
  31
  32         reg = PWM_ENABLE_MASK;
  33         reg |= pulse_width << PWM_WIDTH_SHIFT;
  34         reg |= freq_divider << PWM_DIVIDER_SHIFT;
  35         writel(reg, &local.pwm[channel].control);
  36         debug("%s: channel=%d, rate=%d\n", __func__, channel, rate);
  37 }
  38
  39 int pwm_request(const void *blob, int node, const char *prop_name)
  40 {
  41         int pwm_node;
  42         u32 data[3];
  43
  44         if (fdtdec_get_int_array(blob, node, prop_name, data,
  45                         ARRAY_SIZE(data))) {
  46                 debug("%s: Cannot decode PWM property '%s'\n", __func__,
  47                       prop_name);
  48                 return -1;
  49         }
  50
  51         pwm_node = fdt_node_offset_by_phandle(blob, data[0]);
  52         if (pwm_node != local.pwm_node) {
  53                 debug("%s: PWM property '%s' phandle %d not recognised"
  54                       "- expecting %d\n", __func__, prop_name, data[0],
  55                       local.pwm_node);
  56                 return -1;
  57         }
  58         if (data[1] >= PWM_NUM_CHANNELS) {
  59                 debug("%s: PWM property '%s': invalid channel %u\n", __func__,
  60                       prop_name, data[1]);
  61                 return -1;
  62         }
  63
  64         /*
  65          * TODO: We could maintain a list of requests, but it might not be
  66          * worth it for U-Boot.
  67          */
  68         return data[1];
  69 }
  70
  71 int pwm_init(const void *blob)
  72 {
  73         local.pwm_node = fdtdec_next_compatible(blob, 0,
  74                                                 COMPAT_NVIDIA_TEGRA20_PWM);
  75         if (local.pwm_node < 0) {
  76                 debug("%s: Cannot find device tree node\n", __func__);
  77                 return -1;
  78         }
  79
  80         local.pwm = (struct pwm_ctlr *)fdtdec_get_addr(blob, local.pwm_node,
  81                                                        "reg");
  82         if (local.pwm == (struct pwm_ctlr *)FDT_ADDR_T_NONE) {
  83                 debug("%s: Cannot find pwm reg address\n", __func__);
  84                 return -1;
  85         }
  86         debug("Tegra PWM at %p, node %d\n", local.pwm, local.pwm_node);
  87
  88         return 0;
  89 }