1 /* 2 * Copyright 2012 Freescale Semiconductor, Inc. 3 * 4 * The code contained herein is licensed under the GNU General Public 5 * License. You may obtain a copy of the GNU General Public License 6 * Version 2 or later at the following locations: 7 * 8 * http://www.opensource.org/licenses/gpl-license.html 9 * http://www.gnu.org/copyleft/gpl.html 10 */ 11 12 #include <linux/clk.h> 13 #include <linux/err.h> 14 #include <linux/io.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/of_address.h> 19 #include <linux/pinctrl/consumer.h> 20 #include <linux/platform_device.h> 21 #include <linux/pwm.h> 22 #include <linux/slab.h> 23 #include <linux/stmp_device.h> 24 25 #define SET 0x4 26 #define CLR 0x8 27 #define TOG 0xc 28 29 #define PWM_CTRL 0x0 30 #define PWM_ACTIVE0 0x10 31 #define PWM_PERIOD0 0x20 32 #define PERIOD_PERIOD(p) ((p) & 0xffff) 33 #define PERIOD_PERIOD_MAX 0x10000 34 #define PERIOD_ACTIVE_HIGH (3 << 16) 35 #define PERIOD_INACTIVE_LOW (2 << 18) 36 #define PERIOD_CDIV(div) (((div) & 0x7) << 20) 37 #define PERIOD_CDIV_MAX 8 38 39 struct mxs_pwm_chip { 40 struct pwm_chip chip; 41 struct clk *clk; 42 void __iomem *base; 43 }; 44 45 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip) 46 47 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 48 int duty_ns, int period_ns) 49 { 50 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 51 int ret, div = 0; 52 unsigned int period_cycles, duty_cycles; 53 unsigned long rate; 54 unsigned long long c; 55 56 rate = clk_get_rate(mxs->clk); 57 while (1) { 58 c = rate / (1 << div); 59 c = c * period_ns; 60 do_div(c, 1000000000); 61 if (c < PERIOD_PERIOD_MAX) 62 break; 63 div++; 64 if (div > PERIOD_CDIV_MAX) 65 return -EINVAL; 66 } 67 68 period_cycles = c; 69 c *= duty_ns; 70 do_div(c, period_ns); 71 duty_cycles = c; 72 73 /* 74 * If the PWM channel is disabled, make sure to turn on the clock 75 * before writing the register. Otherwise, keep it enabled. 76 */ 77 if (!test_bit(PWMF_ENABLED, &pwm->flags)) { 78 ret = clk_prepare_enable(mxs->clk); 79 if (ret) 80 return ret; 81 } 82 83 writel(duty_cycles << 16, 84 mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); 85 writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH | 86 PERIOD_INACTIVE_LOW | PERIOD_CDIV(div), 87 mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20); 88 89 /* 90 * If the PWM is not enabled, turn the clock off again to save power. 91 */ 92 if (!test_bit(PWMF_ENABLED, &pwm->flags)) 93 clk_disable_unprepare(mxs->clk); 94 95 return 0; 96 } 97 98 static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 99 { 100 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 101 int ret; 102 103 ret = clk_prepare_enable(mxs->clk); 104 if (ret) 105 return ret; 106 107 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET); 108 109 return 0; 110 } 111 112 static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 113 { 114 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 115 116 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR); 117 118 clk_disable_unprepare(mxs->clk); 119 } 120 121 static const struct pwm_ops mxs_pwm_ops = { 122 .config = mxs_pwm_config, 123 .enable = mxs_pwm_enable, 124 .disable = mxs_pwm_disable, 125 .owner = THIS_MODULE, 126 }; 127 128 static int mxs_pwm_probe(struct platform_device *pdev) 129 { 130 struct device_node *np = pdev->dev.of_node; 131 struct mxs_pwm_chip *mxs; 132 struct resource *res; 133 struct pinctrl *pinctrl; 134 int ret; 135 136 mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL); 137 if (!mxs) 138 return -ENOMEM; 139 140 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 141 mxs->base = devm_ioremap_resource(&pdev->dev, res); 142 if (IS_ERR(mxs->base)) 143 return PTR_ERR(mxs->base); 144 145 pinctrl = devm_pinctrl_get_select_default(&pdev->dev); 146 if (IS_ERR(pinctrl)) 147 return PTR_ERR(pinctrl); 148 149 mxs->clk = devm_clk_get(&pdev->dev, NULL); 150 if (IS_ERR(mxs->clk)) 151 return PTR_ERR(mxs->clk); 152 153 mxs->chip.dev = &pdev->dev; 154 mxs->chip.ops = &mxs_pwm_ops; 155 mxs->chip.base = -1; 156 ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm); 157 if (ret < 0) { 158 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); 159 return ret; 160 } 161 162 ret = pwmchip_add(&mxs->chip); 163 if (ret < 0) { 164 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret); 165 return ret; 166 } 167 168 platform_set_drvdata(pdev, mxs); 169 170 stmp_reset_block(mxs->base); 171 172 return 0; 173 } 174 175 static int mxs_pwm_remove(struct platform_device *pdev) 176 { 177 struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev); 178 179 return pwmchip_remove(&mxs->chip); 180 } 181 182 static const struct of_device_id mxs_pwm_dt_ids[] = { 183 { .compatible = "fsl,imx23-pwm", }, 184 { /* sentinel */ } 185 }; 186 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids); 187 188 static struct platform_driver mxs_pwm_driver = { 189 .driver = { 190 .name = "mxs-pwm", 191 .of_match_table = of_match_ptr(mxs_pwm_dt_ids), 192 }, 193 .probe = mxs_pwm_probe, 194 .remove = mxs_pwm_remove, 195 }; 196 module_platform_driver(mxs_pwm_driver); 197 198 MODULE_ALIAS("platform:mxs-pwm"); 199 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>"); 200 MODULE_DESCRIPTION("Freescale MXS PWM Driver"); 201 MODULE_LICENSE("GPL v2"); 202