1 /* 2 * Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de> 3 * JZ4740 platform PWM support 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License as published by the 7 * Free Software Foundation; either version 2 of the License, or (at your 8 * option) any later version. 9 * 10 * You should have received a copy of the GNU General Public License along 11 * with this program; if not, write to the Free Software Foundation, Inc., 12 * 675 Mass Ave, Cambridge, MA 02139, USA. 13 * 14 */ 15 16 #include <linux/clk.h> 17 #include <linux/err.h> 18 #include <linux/gpio.h> 19 #include <linux/kernel.h> 20 #include <linux/module.h> 21 #include <linux/platform_device.h> 22 #include <linux/pwm.h> 23 24 #include <asm/mach-jz4740/gpio.h> 25 #include <asm/mach-jz4740/timer.h> 26 27 #define NUM_PWM 8 28 29 static const unsigned int jz4740_pwm_gpio_list[NUM_PWM] = { 30 JZ_GPIO_PWM0, 31 JZ_GPIO_PWM1, 32 JZ_GPIO_PWM2, 33 JZ_GPIO_PWM3, 34 JZ_GPIO_PWM4, 35 JZ_GPIO_PWM5, 36 JZ_GPIO_PWM6, 37 JZ_GPIO_PWM7, 38 }; 39 40 struct jz4740_pwm_chip { 41 struct pwm_chip chip; 42 struct clk *clk; 43 }; 44 45 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip) 46 { 47 return container_of(chip, struct jz4740_pwm_chip, chip); 48 } 49 50 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 51 { 52 unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm]; 53 int ret; 54 55 /* 56 * Timers 0 and 1 are used for system tasks, so they are unavailable 57 * for use as PWMs. 58 */ 59 if (pwm->hwpwm < 2) 60 return -EBUSY; 61 62 ret = gpio_request(gpio, pwm->label); 63 if (ret) { 64 dev_err(chip->dev, "Failed to request GPIO#%u for PWM: %d\n", 65 gpio, ret); 66 return ret; 67 } 68 69 jz_gpio_set_function(gpio, JZ_GPIO_FUNC_PWM); 70 71 jz4740_timer_start(pwm->hwpwm); 72 73 return 0; 74 } 75 76 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 77 { 78 unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm]; 79 80 jz4740_timer_set_ctrl(pwm->hwpwm, 0); 81 82 jz_gpio_set_function(gpio, JZ_GPIO_FUNC_NONE); 83 gpio_free(gpio); 84 85 jz4740_timer_stop(pwm->hwpwm); 86 } 87 88 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 89 { 90 uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm); 91 92 ctrl |= JZ_TIMER_CTRL_PWM_ENABLE; 93 jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 94 jz4740_timer_enable(pwm->hwpwm); 95 96 return 0; 97 } 98 99 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 100 { 101 uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm); 102 103 ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE; 104 jz4740_timer_disable(pwm->hwpwm); 105 jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 106 } 107 108 static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 109 int duty_ns, int period_ns) 110 { 111 struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip); 112 unsigned long long tmp; 113 unsigned long period, duty; 114 unsigned int prescaler = 0; 115 uint16_t ctrl; 116 bool is_enabled; 117 118 tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns; 119 do_div(tmp, 1000000000); 120 period = tmp; 121 122 while (period > 0xffff && prescaler < 6) { 123 period >>= 2; 124 ++prescaler; 125 } 126 127 if (prescaler == 6) 128 return -EINVAL; 129 130 tmp = (unsigned long long)period * duty_ns; 131 do_div(tmp, period_ns); 132 duty = period - tmp; 133 134 if (duty >= period) 135 duty = period - 1; 136 137 is_enabled = jz4740_timer_is_enabled(pwm->hwpwm); 138 if (is_enabled) 139 jz4740_pwm_disable(chip, pwm); 140 141 jz4740_timer_set_count(pwm->hwpwm, 0); 142 jz4740_timer_set_duty(pwm->hwpwm, duty); 143 jz4740_timer_set_period(pwm->hwpwm, period); 144 145 ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT | 146 JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN; 147 148 jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 149 150 if (is_enabled) 151 jz4740_pwm_enable(chip, pwm); 152 153 return 0; 154 } 155 156 static const struct pwm_ops jz4740_pwm_ops = { 157 .request = jz4740_pwm_request, 158 .free = jz4740_pwm_free, 159 .config = jz4740_pwm_config, 160 .enable = jz4740_pwm_enable, 161 .disable = jz4740_pwm_disable, 162 .owner = THIS_MODULE, 163 }; 164 165 static int jz4740_pwm_probe(struct platform_device *pdev) 166 { 167 struct jz4740_pwm_chip *jz4740; 168 169 jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL); 170 if (!jz4740) 171 return -ENOMEM; 172 173 jz4740->clk = devm_clk_get(&pdev->dev, "ext"); 174 if (IS_ERR(jz4740->clk)) 175 return PTR_ERR(jz4740->clk); 176 177 jz4740->chip.dev = &pdev->dev; 178 jz4740->chip.ops = &jz4740_pwm_ops; 179 jz4740->chip.npwm = NUM_PWM; 180 jz4740->chip.base = -1; 181 182 platform_set_drvdata(pdev, jz4740); 183 184 return pwmchip_add(&jz4740->chip); 185 } 186 187 static int jz4740_pwm_remove(struct platform_device *pdev) 188 { 189 struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev); 190 191 return pwmchip_remove(&jz4740->chip); 192 } 193 194 static struct platform_driver jz4740_pwm_driver = { 195 .driver = { 196 .name = "jz4740-pwm", 197 }, 198 .probe = jz4740_pwm_probe, 199 .remove = jz4740_pwm_remove, 200 }; 201 module_platform_driver(jz4740_pwm_driver); 202 203 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>"); 204 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver"); 205 MODULE_ALIAS("platform:jz4740-pwm"); 206 MODULE_LICENSE("GPL"); 207