1 /* 2 * Tegra pulse width frequency modulator definitions 3 * 4 * Copyright (c) 2011 The Chromium OS Authors. 5 * See file CREDITS for list of people who contributed to this 6 * project. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as 10 * published by the Free Software Foundation; either version 2 of 11 * the License, or (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 21 * MA 02111-1307 USA 22 */ 23 24 #ifndef __ASM_ARCH_TEGRA_PWM_H 25 #define __ASM_ARCH_TEGRA_PWM_H 26 27 /* This is a single PWM channel */ 28 struct pwm_ctlr { 29 uint control; /* Control register */ 30 uint reserved[3]; /* Space space */ 31 }; 32 33 #define PWM_NUM_CHANNELS 4 34 35 /* PWM_CONTROLLER_PWM_CSR_0/1/2/3_0 */ 36 #define PWM_ENABLE_SHIFT 31 37 #define PWM_ENABLE_MASK (0x1 << PWM_ENABLE_SHIFT) 38 39 #define PWM_WIDTH_SHIFT 16 40 #define PWM_WIDTH_MASK (0x7FFF << PWM_WIDTH_SHIFT) 41 42 #define PWM_DIVIDER_SHIFT 0 43 #define PWM_DIVIDER_MASK (0x1FFF << PWM_DIVIDER_SHIFT) 44 45 /** 46 * Program the PWM with the given parameters. 47 * 48 * @param channel PWM channel to update 49 * @param rate Clock rate to use for PWM 50 * @param pulse_width high pulse width: 0=always low, 1=1/256 pulse high, 51 * n = n/256 pulse high 52 * @param freq_divider frequency divider value (1 to use rate as is) 53 */ 54 void pwm_enable(unsigned channel, int rate, int pulse_width, int freq_divider); 55 56 /** 57 * Request a pwm channel as referenced by a device tree node. 58 * 59 * This channel can then be passed to pwm_enable(). 60 * 61 * @param blob Device tree blob 62 * @param node Node containing reference to pwm 63 * @param prop_name Property name of pwm reference 64 * @return channel number, if ok, else -1 65 */ 66 int pwm_request(const void *blob, int node, const char *prop_name); 67 68 /** 69 * Set up the pwm controller, by looking it up in the fdt. 70 * 71 * @return 0 if ok, -1 if the device tree node was not found or invalid. 72 */ 73 int pwm_init(const void *blob); 74 75 #endif /* __ASM_ARCH_TEGRA_PWM_H */ 76