The pulse width/frequency modulation peripheral supports generating a repeating pulse. It is useful for controlling LCD brightness. Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Tom Warren <twarren@nvidia.com>master
parent
eefe3e598e
commit
e1ae0d1f71
@ -0,0 +1,101 @@ |
||||
/*
|
||||
* Tegra2 pulse width frequency modulator definitions |
||||
* |
||||
* Copyright (c) 2011 The Chromium OS Authors. |
||||
* See file CREDITS for list of people who contributed to this |
||||
* project. |
||||
* |
||||
* This program is free software; you can redistribute it and/or |
||||
* modify it under the terms of the GNU General Public License as |
||||
* published by the Free Software Foundation; either version 2 of |
||||
* the License, or (at your option) any later version. |
||||
* |
||||
* This program is distributed in the hope that it will be useful, |
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
||||
* GNU General Public License for more details. |
||||
* |
||||
* You should have received a copy of the GNU General Public License |
||||
* along with this program; if not, write to the Free Software |
||||
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, |
||||
* MA 02111-1307 USA |
||||
*/ |
||||
|
||||
#include <common.h> |
||||
#include <fdtdec.h> |
||||
#include <asm/io.h> |
||||
#include <asm/arch/clock.h> |
||||
#include <asm/arch/pwm.h> |
||||
|
||||
struct pwm_info { |
||||
struct pwm_ctlr *pwm; /* Registers for our pwm controller */ |
||||
int pwm_node; /* PWM device tree node */ |
||||
} local; |
||||
|
||||
void pwm_enable(unsigned channel, int rate, int pulse_width, int freq_divider) |
||||
{ |
||||
u32 reg; |
||||
|
||||
assert(channel < PWM_NUM_CHANNELS); |
||||
|
||||
/* TODO: Can we use clock_adjust_periph_pll_div() here? */ |
||||
clock_start_periph_pll(PERIPH_ID_PWM, CLOCK_ID_SFROM32KHZ, rate); |
||||
|
||||
reg = PWM_ENABLE_MASK; |
||||
reg |= pulse_width << PWM_WIDTH_SHIFT; |
||||
reg |= freq_divider << PWM_DIVIDER_SHIFT; |
||||
writel(reg, &local.pwm[channel].control); |
||||
debug("%s: channel=%d, rate=%d\n", __func__, channel, rate); |
||||
} |
||||
|
||||
int pwm_request(const void *blob, int node, const char *prop_name) |
||||
{ |
||||
int pwm_node; |
||||
u32 data[3]; |
||||
|
||||
if (fdtdec_get_int_array(blob, node, prop_name, data, |
||||
ARRAY_SIZE(data))) { |
||||
debug("%s: Cannot decode PWM property '%s'\n", __func__, |
||||
prop_name); |
||||
return -1; |
||||
} |
||||
|
||||
pwm_node = fdt_node_offset_by_phandle(blob, data[0]); |
||||
if (pwm_node != local.pwm_node) { |
||||
debug("%s: PWM property '%s' phandle %d not recognised" |
||||
"- expecting %d\n", __func__, prop_name, data[0], |
||||
local.pwm_node); |
||||
return -1; |
||||
} |
||||
if (data[1] >= PWM_NUM_CHANNELS) { |
||||
debug("%s: PWM property '%s': invalid channel %u\n", __func__, |
||||
prop_name, data[1]); |
||||
return -1; |
||||
} |
||||
|
||||
/*
|
||||
* TODO: We could maintain a list of requests, but it might not be |
||||
* worth it for U-Boot. |
||||
*/ |
||||
return data[1]; |
||||
} |
||||
|
||||
int pwm_init(const void *blob) |
||||
{ |
||||
local.pwm_node = fdtdec_next_compatible(blob, 0, |
||||
COMPAT_NVIDIA_TEGRA20_PWM); |
||||
if (local.pwm_node < 0) { |
||||
debug("%s: Cannot find device tree node\n", __func__); |
||||
return -1; |
||||
} |
||||
|
||||
local.pwm = (struct pwm_ctlr *)fdtdec_get_addr(blob, local.pwm_node, |
||||
"reg"); |
||||
if (local.pwm == (struct pwm_ctlr *)FDT_ADDR_T_NONE) { |
||||
debug("%s: Cannot find pwm reg address\n", __func__); |
||||
return -1; |
||||
} |
||||
debug("Tegra PWM at %p, node %d\n", local.pwm, local.pwm_node); |
||||
|
||||
return 0; |
||||
} |
@ -0,0 +1,75 @@ |
||||
/*
|
||||
* Tegra pulse width frequency modulator definitions |
||||
* |
||||
* Copyright (c) 2011 The Chromium OS Authors. |
||||
* See file CREDITS for list of people who contributed to this |
||||
* project. |
||||
* |
||||
* This program is free software; you can redistribute it and/or |
||||
* modify it under the terms of the GNU General Public License as |
||||
* published by the Free Software Foundation; either version 2 of |
||||
* the License, or (at your option) any later version. |
||||
* |
||||
* This program is distributed in the hope that it will be useful, |
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
||||
* GNU General Public License for more details. |
||||
* |
||||
* You should have received a copy of the GNU General Public License |
||||
* along with this program; if not, write to the Free Software |
||||
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, |
||||
* MA 02111-1307 USA |
||||
*/ |
||||
|
||||
#ifndef __ASM_ARCH_TEGRA_PWM_H |
||||
#define __ASM_ARCH_TEGRA_PWM_H |
||||
|
||||
/* This is a single PWM channel */ |
||||
struct pwm_ctlr { |
||||
uint control; /* Control register */ |
||||
uint reserved[3]; /* Space space */ |
||||
}; |
||||
|
||||
#define PWM_NUM_CHANNELS 4 |
||||
|
||||
/* PWM_CONTROLLER_PWM_CSR_0/1/2/3_0 */ |
||||
#define PWM_ENABLE_SHIFT 31 |
||||
#define PWM_ENABLE_MASK (0x1 << PWM_ENABLE_SHIFT) |
||||
|
||||
#define PWM_WIDTH_SHIFT 16 |
||||
#define PWM_WIDTH_MASK (0x7FFF << PWM_WIDTH_SHIFT) |
||||
|
||||
#define PWM_DIVIDER_SHIFT 0 |
||||
#define PWM_DIVIDER_MASK (0x1FFF << PWM_DIVIDER_SHIFT) |
||||
|
||||
/**
|
||||
* Program the PWM with the given parameters. |
||||
* |
||||
* @param channel PWM channel to update |
||||
* @param rate Clock rate to use for PWM |
||||
* @param pulse_width high pulse width: 0=always low, 1=1/256 pulse high, |
||||
* n = n/256 pulse high |
||||
* @param freq_divider frequency divider value (1 to use rate as is) |
||||
*/ |
||||
void pwm_enable(unsigned channel, int rate, int pulse_width, int freq_divider); |
||||
|
||||
/**
|
||||
* Request a pwm channel as referenced by a device tree node. |
||||
* |
||||
* This channel can then be passed to pwm_enable(). |
||||
* |
||||
* @param blob Device tree blob |
||||
* @param node Node containing reference to pwm |
||||
* @param prop_name Property name of pwm reference |
||||
* @return channel number, if ok, else -1 |
||||
*/ |
||||
int pwm_request(const void *blob, int node, const char *prop_name); |
||||
|
||||
/**
|
||||
* Set up the pwm controller, by looking it up in the fdt. |
||||
* |
||||
* @return 0 if ok, -1 if the device tree node was not found or invalid. |
||||
*/ |
||||
int pwm_init(const void *blob); |
||||
|
||||
#endif /* __ASM_ARCH_TEGRA_PWM_H */ |
Loading…
Reference in new issue