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