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 device *dev; 42 struct clk *clk; 43 void __iomem *base; 44 }; 45 46 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip) 47 48 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 49 int duty_ns, int period_ns) 50 { 51 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 52 int ret, div = 0; 53 unsigned int period_cycles, duty_cycles; 54 unsigned long rate; 55 unsigned long long c; 56 57 rate = clk_get_rate(mxs->clk); 58 while (1) { 59 c = rate / (1 << div); 60 c = c * period_ns; 61 do_div(c, 1000000000); 62 if (c < PERIOD_PERIOD_MAX) 63 break; 64 div++; 65 if (div > PERIOD_CDIV_MAX) 66 return -EINVAL; 67 } 68 69 period_cycles = c; 70 c *= duty_ns; 71 do_div(c, period_ns); 72 duty_cycles = c; 73 74 /* 75 * If the PWM channel is disabled, make sure to turn on the clock 76 * before writing the register. Otherwise, keep it enabled. 77 */ 78 if (!test_bit(PWMF_ENABLED, &pwm->flags)) { 79 ret = clk_prepare_enable(mxs->clk); 80 if (ret) 81 return ret; 82 } 83 84 writel(duty_cycles << 16, 85 mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); 86 writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH | 87 PERIOD_INACTIVE_LOW | PERIOD_CDIV(div), 88 mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20); 89 90 /* 91 * If the PWM is not enabled, turn the clock off again to save power. 92 */ 93 if (!test_bit(PWMF_ENABLED, &pwm->flags)) 94 clk_disable_unprepare(mxs->clk); 95 96 return 0; 97 } 98 99 static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 100 { 101 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 102 int ret; 103 104 ret = clk_prepare_enable(mxs->clk); 105 if (ret) 106 return ret; 107 108 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET); 109 110 return 0; 111 } 112 113 static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 114 { 115 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 116 117 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR); 118 119 clk_disable_unprepare(mxs->clk); 120 } 121 122 static const struct pwm_ops mxs_pwm_ops = { 123 .config = mxs_pwm_config, 124 .enable = mxs_pwm_enable, 125 .disable = mxs_pwm_disable, 126 .owner = THIS_MODULE, 127 }; 128 129 static int mxs_pwm_probe(struct platform_device *pdev) 130 { 131 struct device_node *np = pdev->dev.of_node; 132 struct mxs_pwm_chip *mxs; 133 struct resource *res; 134 struct pinctrl *pinctrl; 135 int ret; 136 137 mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL); 138 if (!mxs) 139 return -ENOMEM; 140 141 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 142 mxs->base = devm_request_and_ioremap(&pdev->dev, res); 143 if (!mxs->base) 144 return -EADDRNOTAVAIL; 145 146 pinctrl = devm_pinctrl_get_select_default(&pdev->dev); 147 if (IS_ERR(pinctrl)) 148 return PTR_ERR(pinctrl); 149 150 mxs->clk = devm_clk_get(&pdev->dev, NULL); 151 if (IS_ERR(mxs->clk)) 152 return PTR_ERR(mxs->clk); 153 154 mxs->chip.dev = &pdev->dev; 155 mxs->chip.ops = &mxs_pwm_ops; 156 mxs->chip.base = -1; 157 ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm); 158 if (ret < 0) { 159 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); 160 return ret; 161 } 162 163 ret = pwmchip_add(&mxs->chip); 164 if (ret < 0) { 165 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret); 166 return ret; 167 } 168 169 mxs->dev = &pdev->dev; 170 platform_set_drvdata(pdev, mxs); 171 172 stmp_reset_block(mxs->base); 173 174 return 0; 175 } 176 177 static int __devexit mxs_pwm_remove(struct platform_device *pdev) 178 { 179 struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev); 180 181 return pwmchip_remove(&mxs->chip); 182 } 183 184 static struct of_device_id mxs_pwm_dt_ids[] = { 185 { .compatible = "fsl,imx23-pwm", }, 186 { /* sentinel */ } 187 }; 188 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids); 189 190 static struct platform_driver mxs_pwm_driver = { 191 .driver = { 192 .name = "mxs-pwm", 193 .of_match_table = of_match_ptr(mxs_pwm_dt_ids), 194 }, 195 .probe = mxs_pwm_probe, 196 .remove = __devexit_p(mxs_pwm_remove), 197 }; 198 module_platform_driver(mxs_pwm_driver); 199 200 MODULE_ALIAS("platform:mxs-pwm"); 201 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>"); 202 MODULE_DESCRIPTION("Freescale MXS PWM Driver"); 203 MODULE_LICENSE("GPL v2"); 204