1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * drivers/pwm/pwm-vt8500.c 4 * 5 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz> 6 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com> 7 */ 8 9 #include <linux/module.h> 10 #include <linux/kernel.h> 11 #include <linux/platform_device.h> 12 #include <linux/slab.h> 13 #include <linux/err.h> 14 #include <linux/io.h> 15 #include <linux/pwm.h> 16 #include <linux/delay.h> 17 #include <linux/clk.h> 18 19 #include <asm/div64.h> 20 21 #include <linux/of.h> 22 #include <linux/of_device.h> 23 #include <linux/of_address.h> 24 25 /* 26 * SoC architecture allocates register space for 4 PWMs but only 27 * 2 are currently implemented. 28 */ 29 #define VT8500_NR_PWMS 2 30 31 #define REG_CTRL(pwm) (((pwm) << 4) + 0x00) 32 #define REG_SCALAR(pwm) (((pwm) << 4) + 0x04) 33 #define REG_PERIOD(pwm) (((pwm) << 4) + 0x08) 34 #define REG_DUTY(pwm) (((pwm) << 4) + 0x0C) 35 #define REG_STATUS 0x40 36 37 #define CTRL_ENABLE BIT(0) 38 #define CTRL_INVERT BIT(1) 39 #define CTRL_AUTOLOAD BIT(2) 40 #define CTRL_STOP_IMM BIT(3) 41 #define CTRL_LOAD_PRESCALE BIT(4) 42 #define CTRL_LOAD_PERIOD BIT(5) 43 44 #define STATUS_CTRL_UPDATE BIT(0) 45 #define STATUS_SCALAR_UPDATE BIT(1) 46 #define STATUS_PERIOD_UPDATE BIT(2) 47 #define STATUS_DUTY_UPDATE BIT(3) 48 #define STATUS_ALL_UPDATE 0x0F 49 50 struct vt8500_chip { 51 struct pwm_chip chip; 52 void __iomem *base; 53 struct clk *clk; 54 }; 55 56 #define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip) 57 58 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) 59 static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask) 60 { 61 int loops = msecs_to_loops(10); 62 u32 mask = bitmask << (nr << 8); 63 64 while ((readl(vt8500->base + REG_STATUS) & mask) && --loops) 65 cpu_relax(); 66 67 if (unlikely(!loops)) 68 dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n", 69 mask); 70 } 71 72 static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 73 int duty_ns, int period_ns) 74 { 75 struct vt8500_chip *vt8500 = to_vt8500_chip(chip); 76 unsigned long long c; 77 unsigned long period_cycles, prescale, pv, dc; 78 int err; 79 u32 val; 80 81 err = clk_enable(vt8500->clk); 82 if (err < 0) { 83 dev_err(chip->dev, "failed to enable clock\n"); 84 return err; 85 } 86 87 c = clk_get_rate(vt8500->clk); 88 c = c * period_ns; 89 do_div(c, 1000000000); 90 period_cycles = c; 91 92 if (period_cycles < 1) 93 period_cycles = 1; 94 prescale = (period_cycles - 1) / 4096; 95 pv = period_cycles / (prescale + 1) - 1; 96 if (pv > 4095) 97 pv = 4095; 98 99 if (prescale > 1023) { 100 clk_disable(vt8500->clk); 101 return -EINVAL; 102 } 103 104 c = (unsigned long long)pv * duty_ns; 105 do_div(c, period_ns); 106 dc = c; 107 108 writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm)); 109 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE); 110 111 writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm)); 112 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE); 113 114 writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm)); 115 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE); 116 117 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); 118 val |= CTRL_AUTOLOAD; 119 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); 120 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); 121 122 clk_disable(vt8500->clk); 123 return 0; 124 } 125 126 static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 127 { 128 struct vt8500_chip *vt8500 = to_vt8500_chip(chip); 129 int err; 130 u32 val; 131 132 err = clk_enable(vt8500->clk); 133 if (err < 0) { 134 dev_err(chip->dev, "failed to enable clock\n"); 135 return err; 136 } 137 138 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); 139 val |= CTRL_ENABLE; 140 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); 141 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); 142 143 return 0; 144 } 145 146 static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 147 { 148 struct vt8500_chip *vt8500 = to_vt8500_chip(chip); 149 u32 val; 150 151 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); 152 val &= ~CTRL_ENABLE; 153 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); 154 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); 155 156 clk_disable(vt8500->clk); 157 } 158 159 static int vt8500_pwm_set_polarity(struct pwm_chip *chip, 160 struct pwm_device *pwm, 161 enum pwm_polarity polarity) 162 { 163 struct vt8500_chip *vt8500 = to_vt8500_chip(chip); 164 u32 val; 165 166 val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); 167 168 if (polarity == PWM_POLARITY_INVERSED) 169 val |= CTRL_INVERT; 170 else 171 val &= ~CTRL_INVERT; 172 173 writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); 174 pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); 175 176 return 0; 177 } 178 179 static const struct pwm_ops vt8500_pwm_ops = { 180 .enable = vt8500_pwm_enable, 181 .disable = vt8500_pwm_disable, 182 .config = vt8500_pwm_config, 183 .set_polarity = vt8500_pwm_set_polarity, 184 .owner = THIS_MODULE, 185 }; 186 187 static const struct of_device_id vt8500_pwm_dt_ids[] = { 188 { .compatible = "via,vt8500-pwm", }, 189 { /* Sentinel */ } 190 }; 191 MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids); 192 193 static int vt8500_pwm_probe(struct platform_device *pdev) 194 { 195 struct vt8500_chip *chip; 196 struct device_node *np = pdev->dev.of_node; 197 int ret; 198 199 if (!np) { 200 dev_err(&pdev->dev, "invalid devicetree node\n"); 201 return -EINVAL; 202 } 203 204 chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); 205 if (chip == NULL) 206 return -ENOMEM; 207 208 chip->chip.dev = &pdev->dev; 209 chip->chip.ops = &vt8500_pwm_ops; 210 chip->chip.npwm = VT8500_NR_PWMS; 211 212 chip->clk = devm_clk_get(&pdev->dev, NULL); 213 if (IS_ERR(chip->clk)) { 214 dev_err(&pdev->dev, "clock source not specified\n"); 215 return PTR_ERR(chip->clk); 216 } 217 218 chip->base = devm_platform_ioremap_resource(pdev, 0); 219 if (IS_ERR(chip->base)) 220 return PTR_ERR(chip->base); 221 222 ret = clk_prepare(chip->clk); 223 if (ret < 0) { 224 dev_err(&pdev->dev, "failed to prepare clock\n"); 225 return ret; 226 } 227 228 ret = pwmchip_add(&chip->chip); 229 if (ret < 0) { 230 dev_err(&pdev->dev, "failed to add PWM chip\n"); 231 clk_unprepare(chip->clk); 232 return ret; 233 } 234 235 platform_set_drvdata(pdev, chip); 236 return ret; 237 } 238 239 static int vt8500_pwm_remove(struct platform_device *pdev) 240 { 241 struct vt8500_chip *chip = platform_get_drvdata(pdev); 242 243 pwmchip_remove(&chip->chip); 244 245 clk_unprepare(chip->clk); 246 247 return 0; 248 } 249 250 static struct platform_driver vt8500_pwm_driver = { 251 .probe = vt8500_pwm_probe, 252 .remove = vt8500_pwm_remove, 253 .driver = { 254 .name = "vt8500-pwm", 255 .of_match_table = vt8500_pwm_dt_ids, 256 }, 257 }; 258 module_platform_driver(vt8500_pwm_driver); 259 260 MODULE_DESCRIPTION("VT8500 PWM Driver"); 261 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>"); 262 MODULE_LICENSE("GPL v2"); 263