drivers/mfd/twl6030-pwm.c

   1 /*
   2  * twl6030_pwm.c
   3  * Driver for PHOENIX (TWL6030) Pulse Width Modulator
   4  *
   5  * Copyright (C) 2010 Texas Instruments
   6  * Author: Hemanth V <hemanthv@ti.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published by
  10  * the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along with
  18  * this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/i2c/twl.h>
  24 #include <linux/slab.h>
  25
  26 #define LED_PWM_CTRL1   0xF4
  27 #define LED_PWM_CTRL2   0xF5
  28
  29 /* Max value for CTRL1 register */
  30 #define PWM_CTRL1_MAX   255
  31
  32 /* Pull down disable */
  33 #define PWM_CTRL2_DIS_PD        (1 << 6)
  34
  35 /* Current control 2.5 milli Amps */
  36 #define PWM_CTRL2_CURR_02       (2 << 4)
  37
  38 /* LED supply source */
  39 #define PWM_CTRL2_SRC_VAC       (1 << 2)
  40
  41 /* LED modes */
  42 #define PWM_CTRL2_MODE_HW       (0 << 0)
  43 #define PWM_CTRL2_MODE_SW       (1 << 0)
  44 #define PWM_CTRL2_MODE_DIS      (2 << 0)
  45
  46 #define PWM_CTRL2_MODE_MASK     0x3
  47
  48 struct pwm_device {
  49         const char *label;
  50         unsigned int pwm_id;
  51 };
  52
  53 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  54 {
  55         u8 duty_cycle;
  56         int ret;
  57
  58         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
  59                 return -EINVAL;
  60
  61         duty_cycle = (duty_ns * PWM_CTRL1_MAX) / period_ns;
  62
  63         ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, duty_cycle, LED_PWM_CTRL1);
  64
  65         if (ret < 0) {
  66                 pr_err("%s: Failed to configure PWM, Error %d\n",
  67                         pwm->label, ret);
  68                 return ret;
  69         }
  70         return 0;
  71 }
  72 EXPORT_SYMBOL(pwm_config);
  73
  74 int pwm_enable(struct pwm_device *pwm)
  75 {
  76         u8 val;
  77         int ret;
  78
  79         ret = twl_i2c_read_u8(TWL6030_MODULE_ID1, &val, LED_PWM_CTRL2);
  80         if (ret < 0) {
  81                 pr_err("%s: Failed to enable PWM, Error %d\n", pwm->label, ret);
  82                 return ret;
  83         }
  84
  85         /* Change mode to software control */
  86         val &= ~PWM_CTRL2_MODE_MASK;
  87         val |= PWM_CTRL2_MODE_SW;
  88
  89         ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, LED_PWM_CTRL2);
  90         if (ret < 0) {
  91                 pr_err("%s: Failed to enable PWM, Error %d\n", pwm->label, ret);
  92                 return ret;
  93         }
  94
  95         twl_i2c_read_u8(TWL6030_MODULE_ID1, &val, LED_PWM_CTRL2);
  96         return 0;
  97 }
  98 EXPORT_SYMBOL(pwm_enable);
  99
 100 void pwm_disable(struct pwm_device *pwm)
 101 {
 102         u8 val;
 103         int ret;
 104
 105         ret = twl_i2c_read_u8(TWL6030_MODULE_ID1, &val, LED_PWM_CTRL2);
 106         if (ret < 0) {
 107                 pr_err("%s: Failed to disable PWM, Error %d\n",
 108                         pwm->label, ret);
 109                 return;
 110         }
 111
 112         val &= ~PWM_CTRL2_MODE_MASK;
 113         val |= PWM_CTRL2_MODE_HW;
 114
 115         ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, LED_PWM_CTRL2);
 116         if (ret < 0) {
 117                 pr_err("%s: Failed to disable PWM, Error %d\n",
 118                         pwm->label, ret);
 119                 return;
 120         }
 121         return;
 122 }
 123 EXPORT_SYMBOL(pwm_disable);
 124
 125 struct pwm_device *pwm_request(int pwm_id, const char *label)
 126 {
 127         u8 val;
 128         int ret;
 129         struct pwm_device *pwm;
 130
 131         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 132         if (pwm == NULL) {
 133                 pr_err("%s: failed to allocate memory\n", label);
 134                 return NULL;
 135         }
 136
 137         pwm->label = label;
 138         pwm->pwm_id = pwm_id;
 139
 140         /* Configure PWM */
 141         val = PWM_CTRL2_DIS_PD | PWM_CTRL2_CURR_02 | PWM_CTRL2_SRC_VAC |
 142                 PWM_CTRL2_MODE_HW;
 143
 144         ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, LED_PWM_CTRL2);
 145
 146         if (ret < 0) {
 147                 pr_err("%s: Failed to configure PWM, Error %d\n",
 148                          pwm->label, ret);
 149
 150                 kfree(pwm);
 151                 return NULL;
 152         }
 153
 154         return pwm;
 155 }
 156 EXPORT_SYMBOL(pwm_request);
 157
 158 void pwm_free(struct pwm_device *pwm)
 159 {
 160         pwm_disable(pwm);
 161         kfree(pwm);
 162 }
 163 EXPORT_SYMBOL(pwm_free);