1 /* 2 * Marvell Berlin PWM driver 3 * 4 * Copyright (C) 2015 Marvell Technology Group Ltd. 5 * 6 * Author: Antoine Tenart <antoine.tenart@free-electrons.com> 7 * 8 * This file is licensed under the terms of the GNU General Public 9 * License version 2. This program is licensed "as is" without any 10 * warranty of any kind, whether express or implied. 11 */ 12 13 #include <linux/clk.h> 14 #include <linux/io.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/platform_device.h> 18 #include <linux/pwm.h> 19 #include <linux/slab.h> 20 21 #define BERLIN_PWM_EN 0x0 22 #define BERLIN_PWM_ENABLE BIT(0) 23 #define BERLIN_PWM_CONTROL 0x4 24 /* 25 * The prescaler claims to support 8 different moduli, configured using the 26 * low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64, 27 * 256, 1024, and 4096.) However, the moduli from 4 to 1024 appear to be 28 * implemented by internally shifting TCNT left without adding additional 29 * bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff; 30 * for 8, 0x1fff; and so on. This means that those moduli are entirely 31 * useless, as we could just do the shift ourselves. The 4096 modulus is 32 * implemented with a real prescaler, so we do use that, but we treat it 33 * as a flag instead of pretending the modulus is actually configurable. 34 */ 35 #define BERLIN_PWM_PRESCALE_4096 0x7 36 #define BERLIN_PWM_INVERT_POLARITY BIT(3) 37 #define BERLIN_PWM_DUTY 0x8 38 #define BERLIN_PWM_TCNT 0xc 39 #define BERLIN_PWM_MAX_TCNT 65535 40 41 struct berlin_pwm_channel { 42 u32 enable; 43 u32 ctrl; 44 u32 duty; 45 u32 tcnt; 46 }; 47 48 struct berlin_pwm_chip { 49 struct pwm_chip chip; 50 struct clk *clk; 51 void __iomem *base; 52 }; 53 54 static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip) 55 { 56 return container_of(chip, struct berlin_pwm_chip, chip); 57 } 58 59 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *chip, 60 unsigned int channel, unsigned long offset) 61 { 62 return readl_relaxed(chip->base + channel * 0x10 + offset); 63 } 64 65 static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip, 66 unsigned int channel, u32 value, 67 unsigned long offset) 68 { 69 writel_relaxed(value, chip->base + channel * 0x10 + offset); 70 } 71 72 static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 73 { 74 struct berlin_pwm_channel *channel; 75 76 channel = kzalloc(sizeof(*channel), GFP_KERNEL); 77 if (!channel) 78 return -ENOMEM; 79 80 return pwm_set_chip_data(pwm, channel); 81 } 82 83 static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 84 { 85 struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm); 86 87 kfree(channel); 88 } 89 90 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev, 91 int duty_ns, int period_ns) 92 { 93 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 94 bool prescale_4096 = false; 95 u32 value, duty, period; 96 u64 cycles; 97 98 cycles = clk_get_rate(pwm->clk); 99 cycles *= period_ns; 100 do_div(cycles, NSEC_PER_SEC); 101 102 if (cycles > BERLIN_PWM_MAX_TCNT) { 103 prescale_4096 = true; 104 cycles >>= 12; // Prescaled by 4096 105 106 if (cycles > BERLIN_PWM_MAX_TCNT) 107 return -ERANGE; 108 } 109 110 period = cycles; 111 cycles *= duty_ns; 112 do_div(cycles, period_ns); 113 duty = cycles; 114 115 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL); 116 if (prescale_4096) 117 value |= BERLIN_PWM_PRESCALE_4096; 118 else 119 value &= ~BERLIN_PWM_PRESCALE_4096; 120 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL); 121 122 berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY); 123 berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT); 124 125 return 0; 126 } 127 128 static int berlin_pwm_set_polarity(struct pwm_chip *chip, 129 struct pwm_device *pwm_dev, 130 enum pwm_polarity polarity) 131 { 132 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 133 u32 value; 134 135 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL); 136 137 if (polarity == PWM_POLARITY_NORMAL) 138 value &= ~BERLIN_PWM_INVERT_POLARITY; 139 else 140 value |= BERLIN_PWM_INVERT_POLARITY; 141 142 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL); 143 144 return 0; 145 } 146 147 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev) 148 { 149 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 150 u32 value; 151 152 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN); 153 value |= BERLIN_PWM_ENABLE; 154 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN); 155 156 return 0; 157 } 158 159 static void berlin_pwm_disable(struct pwm_chip *chip, 160 struct pwm_device *pwm_dev) 161 { 162 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip); 163 u32 value; 164 165 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN); 166 value &= ~BERLIN_PWM_ENABLE; 167 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN); 168 } 169 170 static const struct pwm_ops berlin_pwm_ops = { 171 .request = berlin_pwm_request, 172 .free = berlin_pwm_free, 173 .config = berlin_pwm_config, 174 .set_polarity = berlin_pwm_set_polarity, 175 .enable = berlin_pwm_enable, 176 .disable = berlin_pwm_disable, 177 .owner = THIS_MODULE, 178 }; 179 180 static const struct of_device_id berlin_pwm_match[] = { 181 { .compatible = "marvell,berlin-pwm" }, 182 { }, 183 }; 184 MODULE_DEVICE_TABLE(of, berlin_pwm_match); 185 186 static int berlin_pwm_probe(struct platform_device *pdev) 187 { 188 struct berlin_pwm_chip *pwm; 189 int ret; 190 191 pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); 192 if (!pwm) 193 return -ENOMEM; 194 195 pwm->base = devm_platform_ioremap_resource(pdev, 0); 196 if (IS_ERR(pwm->base)) 197 return PTR_ERR(pwm->base); 198 199 pwm->clk = devm_clk_get(&pdev->dev, NULL); 200 if (IS_ERR(pwm->clk)) 201 return PTR_ERR(pwm->clk); 202 203 ret = clk_prepare_enable(pwm->clk); 204 if (ret) 205 return ret; 206 207 pwm->chip.dev = &pdev->dev; 208 pwm->chip.ops = &berlin_pwm_ops; 209 pwm->chip.base = -1; 210 pwm->chip.npwm = 4; 211 pwm->chip.of_xlate = of_pwm_xlate_with_flags; 212 pwm->chip.of_pwm_n_cells = 3; 213 214 ret = pwmchip_add(&pwm->chip); 215 if (ret < 0) { 216 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); 217 clk_disable_unprepare(pwm->clk); 218 return ret; 219 } 220 221 platform_set_drvdata(pdev, pwm); 222 223 return 0; 224 } 225 226 static int berlin_pwm_remove(struct platform_device *pdev) 227 { 228 struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev); 229 int ret; 230 231 ret = pwmchip_remove(&pwm->chip); 232 clk_disable_unprepare(pwm->clk); 233 234 return ret; 235 } 236 237 #ifdef CONFIG_PM_SLEEP 238 static int berlin_pwm_suspend(struct device *dev) 239 { 240 struct berlin_pwm_chip *pwm = dev_get_drvdata(dev); 241 unsigned int i; 242 243 for (i = 0; i < pwm->chip.npwm; i++) { 244 struct berlin_pwm_channel *channel; 245 246 channel = pwm_get_chip_data(&pwm->chip.pwms[i]); 247 if (!channel) 248 continue; 249 250 channel->enable = berlin_pwm_readl(pwm, i, BERLIN_PWM_ENABLE); 251 channel->ctrl = berlin_pwm_readl(pwm, i, BERLIN_PWM_CONTROL); 252 channel->duty = berlin_pwm_readl(pwm, i, BERLIN_PWM_DUTY); 253 channel->tcnt = berlin_pwm_readl(pwm, i, BERLIN_PWM_TCNT); 254 } 255 256 clk_disable_unprepare(pwm->clk); 257 258 return 0; 259 } 260 261 static int berlin_pwm_resume(struct device *dev) 262 { 263 struct berlin_pwm_chip *pwm = dev_get_drvdata(dev); 264 unsigned int i; 265 int ret; 266 267 ret = clk_prepare_enable(pwm->clk); 268 if (ret) 269 return ret; 270 271 for (i = 0; i < pwm->chip.npwm; i++) { 272 struct berlin_pwm_channel *channel; 273 274 channel = pwm_get_chip_data(&pwm->chip.pwms[i]); 275 if (!channel) 276 continue; 277 278 berlin_pwm_writel(pwm, i, channel->ctrl, BERLIN_PWM_CONTROL); 279 berlin_pwm_writel(pwm, i, channel->duty, BERLIN_PWM_DUTY); 280 berlin_pwm_writel(pwm, i, channel->tcnt, BERLIN_PWM_TCNT); 281 berlin_pwm_writel(pwm, i, channel->enable, BERLIN_PWM_ENABLE); 282 } 283 284 return 0; 285 } 286 #endif 287 288 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend, 289 berlin_pwm_resume); 290 291 static struct platform_driver berlin_pwm_driver = { 292 .probe = berlin_pwm_probe, 293 .remove = berlin_pwm_remove, 294 .driver = { 295 .name = "berlin-pwm", 296 .of_match_table = berlin_pwm_match, 297 .pm = &berlin_pwm_pm_ops, 298 }, 299 }; 300 module_platform_driver(berlin_pwm_driver); 301 302 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>"); 303 MODULE_DESCRIPTION("Marvell Berlin PWM driver"); 304 MODULE_LICENSE("GPL v2"); 305