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/timer.h> 25 26 #define NUM_PWM 8 27 28 struct jz4740_pwm_chip { 29 struct pwm_chip chip; 30 struct clk *clk; 31 }; 32 33 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip) 34 { 35 return container_of(chip, struct jz4740_pwm_chip, chip); 36 } 37 38 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 39 { 40 /* 41 * Timers 0 and 1 are used for system tasks, so they are unavailable 42 * for use as PWMs. 43 */ 44 if (pwm->hwpwm < 2) 45 return -EBUSY; 46 47 jz4740_timer_start(pwm->hwpwm); 48 49 return 0; 50 } 51 52 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 53 { 54 jz4740_timer_set_ctrl(pwm->hwpwm, 0); 55 56 jz4740_timer_stop(pwm->hwpwm); 57 } 58 59 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 60 { 61 uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm); 62 63 ctrl |= JZ_TIMER_CTRL_PWM_ENABLE; 64 jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 65 jz4740_timer_enable(pwm->hwpwm); 66 67 return 0; 68 } 69 70 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 71 { 72 uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm); 73 74 ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE; 75 jz4740_timer_disable(pwm->hwpwm); 76 jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 77 } 78 79 static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 80 int duty_ns, int period_ns) 81 { 82 struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip); 83 unsigned long long tmp; 84 unsigned long period, duty; 85 unsigned int prescaler = 0; 86 uint16_t ctrl; 87 bool is_enabled; 88 89 tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns; 90 do_div(tmp, 1000000000); 91 period = tmp; 92 93 while (period > 0xffff && prescaler < 6) { 94 period >>= 2; 95 ++prescaler; 96 } 97 98 if (prescaler == 6) 99 return -EINVAL; 100 101 tmp = (unsigned long long)period * duty_ns; 102 do_div(tmp, period_ns); 103 duty = period - tmp; 104 105 if (duty >= period) 106 duty = period - 1; 107 108 is_enabled = jz4740_timer_is_enabled(pwm->hwpwm); 109 if (is_enabled) 110 jz4740_pwm_disable(chip, pwm); 111 112 jz4740_timer_set_count(pwm->hwpwm, 0); 113 jz4740_timer_set_duty(pwm->hwpwm, duty); 114 jz4740_timer_set_period(pwm->hwpwm, period); 115 116 ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT | 117 JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN; 118 119 jz4740_timer_set_ctrl(pwm->hwpwm, ctrl); 120 121 if (is_enabled) 122 jz4740_pwm_enable(chip, pwm); 123 124 return 0; 125 } 126 127 static const struct pwm_ops jz4740_pwm_ops = { 128 .request = jz4740_pwm_request, 129 .free = jz4740_pwm_free, 130 .config = jz4740_pwm_config, 131 .enable = jz4740_pwm_enable, 132 .disable = jz4740_pwm_disable, 133 .owner = THIS_MODULE, 134 }; 135 136 static int jz4740_pwm_probe(struct platform_device *pdev) 137 { 138 struct jz4740_pwm_chip *jz4740; 139 140 jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL); 141 if (!jz4740) 142 return -ENOMEM; 143 144 jz4740->clk = devm_clk_get(&pdev->dev, "ext"); 145 if (IS_ERR(jz4740->clk)) 146 return PTR_ERR(jz4740->clk); 147 148 jz4740->chip.dev = &pdev->dev; 149 jz4740->chip.ops = &jz4740_pwm_ops; 150 jz4740->chip.npwm = NUM_PWM; 151 jz4740->chip.base = -1; 152 153 platform_set_drvdata(pdev, jz4740); 154 155 return pwmchip_add(&jz4740->chip); 156 } 157 158 static int jz4740_pwm_remove(struct platform_device *pdev) 159 { 160 struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev); 161 162 return pwmchip_remove(&jz4740->chip); 163 } 164 165 static struct platform_driver jz4740_pwm_driver = { 166 .driver = { 167 .name = "jz4740-pwm", 168 }, 169 .probe = jz4740_pwm_probe, 170 .remove = jz4740_pwm_remove, 171 }; 172 module_platform_driver(jz4740_pwm_driver); 173 174 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>"); 175 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver"); 176 MODULE_ALIAS("platform:jz4740-pwm"); 177 MODULE_LICENSE("GPL"); 178