1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright 2012 Freescale Semiconductor, Inc. 4 */ 5 6 #include <linux/clk.h> 7 #include <linux/err.h> 8 #include <linux/io.h> 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/of.h> 12 #include <linux/platform_device.h> 13 #include <linux/pwm.h> 14 #include <linux/slab.h> 15 #include <linux/stmp_device.h> 16 17 #define SET 0x4 18 #define CLR 0x8 19 #define TOG 0xc 20 21 #define PWM_CTRL 0x0 22 #define PWM_ACTIVE0 0x10 23 #define PWM_PERIOD0 0x20 24 #define PERIOD_PERIOD(p) ((p) & 0xffff) 25 #define PERIOD_PERIOD_MAX 0x10000 26 #define PERIOD_ACTIVE_HIGH (3 << 16) 27 #define PERIOD_ACTIVE_LOW (2 << 16) 28 #define PERIOD_INACTIVE_HIGH (3 << 18) 29 #define PERIOD_INACTIVE_LOW (2 << 18) 30 #define PERIOD_POLARITY_NORMAL (PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW) 31 #define PERIOD_POLARITY_INVERSE (PERIOD_ACTIVE_LOW | PERIOD_INACTIVE_HIGH) 32 #define PERIOD_CDIV(div) (((div) & 0x7) << 20) 33 #define PERIOD_CDIV_MAX 8 34 35 static const u8 cdiv_shift[PERIOD_CDIV_MAX] = { 36 0, 1, 2, 3, 4, 6, 8, 10 37 }; 38 39 struct mxs_pwm_chip { 40 struct clk *clk; 41 void __iomem *base; 42 }; 43 44 static inline struct mxs_pwm_chip *to_mxs_pwm_chip(struct pwm_chip *chip) 45 { 46 return pwmchip_get_drvdata(chip); 47 } 48 49 static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 50 const struct pwm_state *state) 51 { 52 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 53 int ret, div = 0; 54 unsigned int period_cycles, duty_cycles; 55 unsigned long rate; 56 unsigned long long c; 57 unsigned int pol_bits; 58 59 /* 60 * If the PWM channel is disabled, make sure to turn on the 61 * clock before calling clk_get_rate() and writing to the 62 * registers. Otherwise, just keep it enabled. 63 */ 64 if (!pwm_is_enabled(pwm)) { 65 ret = clk_prepare_enable(mxs->clk); 66 if (ret) 67 return ret; 68 } 69 70 if (!state->enabled && pwm_is_enabled(pwm)) 71 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR); 72 73 rate = clk_get_rate(mxs->clk); 74 while (1) { 75 c = rate >> cdiv_shift[div]; 76 c = c * state->period; 77 do_div(c, 1000000000); 78 if (c < PERIOD_PERIOD_MAX) 79 break; 80 div++; 81 if (div >= PERIOD_CDIV_MAX) 82 return -EINVAL; 83 } 84 85 period_cycles = c; 86 c *= state->duty_cycle; 87 do_div(c, state->period); 88 duty_cycles = c; 89 90 /* 91 * The data sheet the says registers must be written to in 92 * this order (ACTIVEn, then PERIODn). Also, the new settings 93 * only take effect at the beginning of a new period, avoiding 94 * glitches. 95 */ 96 97 pol_bits = state->polarity == PWM_POLARITY_NORMAL ? 98 PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE; 99 writel(duty_cycles << 16, 100 mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); 101 writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div), 102 mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20); 103 104 if (state->enabled) { 105 if (!pwm_is_enabled(pwm)) { 106 /* 107 * The clock was enabled above. Just enable 108 * the channel in the control register. 109 */ 110 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET); 111 } 112 } else { 113 clk_disable_unprepare(mxs->clk); 114 } 115 return 0; 116 } 117 118 static const struct pwm_ops mxs_pwm_ops = { 119 .apply = mxs_pwm_apply, 120 }; 121 122 static int mxs_pwm_probe(struct platform_device *pdev) 123 { 124 struct device_node *np = pdev->dev.of_node; 125 struct pwm_chip *chip; 126 struct mxs_pwm_chip *mxs; 127 u32 npwm; 128 int ret; 129 130 ret = of_property_read_u32(np, "fsl,pwm-number", &npwm); 131 if (ret < 0) { 132 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); 133 return ret; 134 } 135 136 chip = devm_pwmchip_alloc(&pdev->dev, npwm, sizeof(*mxs)); 137 if (IS_ERR(chip)) 138 return PTR_ERR(chip); 139 mxs = to_mxs_pwm_chip(chip); 140 141 mxs->base = devm_platform_ioremap_resource(pdev, 0); 142 if (IS_ERR(mxs->base)) 143 return PTR_ERR(mxs->base); 144 145 mxs->clk = devm_clk_get(&pdev->dev, NULL); 146 if (IS_ERR(mxs->clk)) 147 return PTR_ERR(mxs->clk); 148 149 chip->ops = &mxs_pwm_ops; 150 151 /* FIXME: Only do this if the PWM isn't already running */ 152 ret = stmp_reset_block(mxs->base); 153 if (ret) 154 return dev_err_probe(&pdev->dev, ret, "failed to reset PWM\n"); 155 156 ret = devm_pwmchip_add(&pdev->dev, chip); 157 if (ret < 0) { 158 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret); 159 return ret; 160 } 161 162 return 0; 163 } 164 165 static const struct of_device_id mxs_pwm_dt_ids[] = { 166 { .compatible = "fsl,imx23-pwm", }, 167 { /* sentinel */ } 168 }; 169 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids); 170 171 static struct platform_driver mxs_pwm_driver = { 172 .driver = { 173 .name = "mxs-pwm", 174 .of_match_table = mxs_pwm_dt_ids, 175 }, 176 .probe = mxs_pwm_probe, 177 }; 178 module_platform_driver(mxs_pwm_driver); 179 180 MODULE_ALIAS("platform:mxs-pwm"); 181 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>"); 182 MODULE_DESCRIPTION("Freescale MXS PWM Driver"); 183 MODULE_LICENSE("GPL v2"); 184