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/platform_device.h> 20 #include <linux/pwm.h> 21 #include <linux/slab.h> 22 #include <linux/stmp_device.h> 23 24 #define SET 0x4 25 #define CLR 0x8 26 #define TOG 0xc 27 28 #define PWM_CTRL 0x0 29 #define PWM_ACTIVE0 0x10 30 #define PWM_PERIOD0 0x20 31 #define PERIOD_PERIOD(p) ((p) & 0xffff) 32 #define PERIOD_PERIOD_MAX 0x10000 33 #define PERIOD_ACTIVE_HIGH (3 << 16) 34 #define PERIOD_INACTIVE_LOW (2 << 18) 35 #define PERIOD_CDIV(div) (((div) & 0x7) << 20) 36 #define PERIOD_CDIV_MAX 8 37 38 static const unsigned int cdiv[PERIOD_CDIV_MAX] = { 39 1, 2, 4, 8, 16, 64, 256, 1024 40 }; 41 42 struct mxs_pwm_chip { 43 struct pwm_chip chip; 44 struct clk *clk; 45 void __iomem *base; 46 }; 47 48 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip) 49 50 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 51 int duty_ns, int period_ns) 52 { 53 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 54 int ret, div = 0; 55 unsigned int period_cycles, duty_cycles; 56 unsigned long rate; 57 unsigned long long c; 58 59 rate = clk_get_rate(mxs->clk); 60 while (1) { 61 c = rate / cdiv[div]; 62 c = c * period_ns; 63 do_div(c, 1000000000); 64 if (c < PERIOD_PERIOD_MAX) 65 break; 66 div++; 67 if (div >= PERIOD_CDIV_MAX) 68 return -EINVAL; 69 } 70 71 period_cycles = c; 72 c *= duty_ns; 73 do_div(c, period_ns); 74 duty_cycles = c; 75 76 /* 77 * If the PWM channel is disabled, make sure to turn on the clock 78 * before writing the register. Otherwise, keep it enabled. 79 */ 80 if (!pwm_is_enabled(pwm)) { 81 ret = clk_prepare_enable(mxs->clk); 82 if (ret) 83 return ret; 84 } 85 86 writel(duty_cycles << 16, 87 mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); 88 writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH | 89 PERIOD_INACTIVE_LOW | PERIOD_CDIV(div), 90 mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20); 91 92 /* 93 * If the PWM is not enabled, turn the clock off again to save power. 94 */ 95 if (!pwm_is_enabled(pwm)) 96 clk_disable_unprepare(mxs->clk); 97 98 return 0; 99 } 100 101 static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 102 { 103 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 104 int ret; 105 106 ret = clk_prepare_enable(mxs->clk); 107 if (ret) 108 return ret; 109 110 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET); 111 112 return 0; 113 } 114 115 static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 116 { 117 struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); 118 119 writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR); 120 121 clk_disable_unprepare(mxs->clk); 122 } 123 124 static const struct pwm_ops mxs_pwm_ops = { 125 .config = mxs_pwm_config, 126 .enable = mxs_pwm_enable, 127 .disable = mxs_pwm_disable, 128 .owner = THIS_MODULE, 129 }; 130 131 static int mxs_pwm_probe(struct platform_device *pdev) 132 { 133 struct device_node *np = pdev->dev.of_node; 134 struct mxs_pwm_chip *mxs; 135 struct resource *res; 136 int ret; 137 138 mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL); 139 if (!mxs) 140 return -ENOMEM; 141 142 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 143 mxs->base = devm_ioremap_resource(&pdev->dev, res); 144 if (IS_ERR(mxs->base)) 145 return PTR_ERR(mxs->base); 146 147 mxs->clk = devm_clk_get(&pdev->dev, NULL); 148 if (IS_ERR(mxs->clk)) 149 return PTR_ERR(mxs->clk); 150 151 mxs->chip.dev = &pdev->dev; 152 mxs->chip.ops = &mxs_pwm_ops; 153 mxs->chip.base = -1; 154 mxs->chip.can_sleep = true; 155 ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm); 156 if (ret < 0) { 157 dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); 158 return ret; 159 } 160 161 ret = pwmchip_add(&mxs->chip); 162 if (ret < 0) { 163 dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret); 164 return ret; 165 } 166 167 platform_set_drvdata(pdev, mxs); 168 169 ret = stmp_reset_block(mxs->base); 170 if (ret) 171 goto pwm_remove; 172 173 return 0; 174 175 pwm_remove: 176 pwmchip_remove(&mxs->chip); 177 return ret; 178 } 179 180 static int mxs_pwm_remove(struct platform_device *pdev) 181 { 182 struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev); 183 184 return pwmchip_remove(&mxs->chip); 185 } 186 187 static const struct of_device_id mxs_pwm_dt_ids[] = { 188 { .compatible = "fsl,imx23-pwm", }, 189 { /* sentinel */ } 190 }; 191 MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids); 192 193 static struct platform_driver mxs_pwm_driver = { 194 .driver = { 195 .name = "mxs-pwm", 196 .of_match_table = mxs_pwm_dt_ids, 197 }, 198 .probe = mxs_pwm_probe, 199 .remove = mxs_pwm_remove, 200 }; 201 module_platform_driver(mxs_pwm_driver); 202 203 MODULE_ALIAS("platform:mxs-pwm"); 204 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>"); 205 MODULE_DESCRIPTION("Freescale MXS PWM Driver"); 206 MODULE_LICENSE("GPL v2"); 207