1 /* 2 * ECAP PWM driver 3 * 4 * Copyright (C) 2012 Texas Instruments, Inc. - http://www.ti.com/ 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 19 */ 20 21 #include <linux/module.h> 22 #include <linux/platform_device.h> 23 #include <linux/io.h> 24 #include <linux/err.h> 25 #include <linux/clk.h> 26 #include <linux/pm_runtime.h> 27 #include <linux/pwm.h> 28 29 /* ECAP registers and bits definitions */ 30 #define CAP1 0x08 31 #define CAP2 0x0C 32 #define CAP3 0x10 33 #define CAP4 0x14 34 #define ECCTL2 0x2A 35 #define ECCTL2_APWM_MODE BIT(9) 36 #define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6)) 37 #define ECCTL2_TSCTR_FREERUN BIT(4) 38 39 struct ecap_pwm_chip { 40 struct pwm_chip chip; 41 unsigned int clk_rate; 42 void __iomem *mmio_base; 43 }; 44 45 static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip) 46 { 47 return container_of(chip, struct ecap_pwm_chip, chip); 48 } 49 50 /* 51 * period_ns = 10^9 * period_cycles / PWM_CLK_RATE 52 * duty_ns = 10^9 * duty_cycles / PWM_CLK_RATE 53 */ 54 static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 55 int duty_ns, int period_ns) 56 { 57 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 58 unsigned long long c; 59 unsigned long period_cycles, duty_cycles; 60 unsigned int reg_val; 61 62 if (period_ns < 0 || duty_ns < 0 || period_ns > NSEC_PER_SEC) 63 return -ERANGE; 64 65 c = pc->clk_rate; 66 c = c * period_ns; 67 do_div(c, NSEC_PER_SEC); 68 period_cycles = (unsigned long)c; 69 70 if (period_cycles < 1) { 71 period_cycles = 1; 72 duty_cycles = 1; 73 } else { 74 c = pc->clk_rate; 75 c = c * duty_ns; 76 do_div(c, NSEC_PER_SEC); 77 duty_cycles = (unsigned long)c; 78 } 79 80 pm_runtime_get_sync(pc->chip.dev); 81 82 reg_val = readw(pc->mmio_base + ECCTL2); 83 84 /* Configure APWM mode & disable sync option */ 85 reg_val |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA; 86 87 writew(reg_val, pc->mmio_base + ECCTL2); 88 89 if (!test_bit(PWMF_ENABLED, &pwm->flags)) { 90 /* Update active registers if not running */ 91 writel(duty_cycles, pc->mmio_base + CAP2); 92 writel(period_cycles, pc->mmio_base + CAP1); 93 } else { 94 /* 95 * Update shadow registers to configure period and 96 * compare values. This helps current PWM period to 97 * complete on reconfiguring 98 */ 99 writel(duty_cycles, pc->mmio_base + CAP4); 100 writel(period_cycles, pc->mmio_base + CAP3); 101 } 102 103 pm_runtime_put_sync(pc->chip.dev); 104 return 0; 105 } 106 107 static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 108 { 109 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 110 unsigned int reg_val; 111 112 /* Leave clock enabled on enabling PWM */ 113 pm_runtime_get_sync(pc->chip.dev); 114 115 /* 116 * Enable 'Free run Time stamp counter mode' to start counter 117 * and 'APWM mode' to enable APWM output 118 */ 119 reg_val = readw(pc->mmio_base + ECCTL2); 120 reg_val |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE; 121 writew(reg_val, pc->mmio_base + ECCTL2); 122 return 0; 123 } 124 125 static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 126 { 127 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 128 unsigned int reg_val; 129 130 /* 131 * Disable 'Free run Time stamp counter mode' to stop counter 132 * and 'APWM mode' to put APWM output to low 133 */ 134 reg_val = readw(pc->mmio_base + ECCTL2); 135 reg_val &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE); 136 writew(reg_val, pc->mmio_base + ECCTL2); 137 138 /* Disable clock on PWM disable */ 139 pm_runtime_put_sync(pc->chip.dev); 140 } 141 142 static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 143 { 144 if (test_bit(PWMF_ENABLED, &pwm->flags)) { 145 dev_warn(chip->dev, "Removing PWM device without disabling\n"); 146 pm_runtime_put_sync(chip->dev); 147 } 148 } 149 150 static const struct pwm_ops ecap_pwm_ops = { 151 .free = ecap_pwm_free, 152 .config = ecap_pwm_config, 153 .enable = ecap_pwm_enable, 154 .disable = ecap_pwm_disable, 155 .owner = THIS_MODULE, 156 }; 157 158 static int __devinit ecap_pwm_probe(struct platform_device *pdev) 159 { 160 int ret; 161 struct resource *r; 162 struct clk *clk; 163 struct ecap_pwm_chip *pc; 164 165 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); 166 if (!pc) { 167 dev_err(&pdev->dev, "failed to allocate memory\n"); 168 return -ENOMEM; 169 } 170 171 clk = devm_clk_get(&pdev->dev, "fck"); 172 if (IS_ERR(clk)) { 173 dev_err(&pdev->dev, "failed to get clock\n"); 174 return PTR_ERR(clk); 175 } 176 177 pc->clk_rate = clk_get_rate(clk); 178 if (!pc->clk_rate) { 179 dev_err(&pdev->dev, "failed to get clock rate\n"); 180 return -EINVAL; 181 } 182 183 pc->chip.dev = &pdev->dev; 184 pc->chip.ops = &ecap_pwm_ops; 185 pc->chip.base = -1; 186 pc->chip.npwm = 1; 187 188 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 189 if (!r) { 190 dev_err(&pdev->dev, "no memory resource defined\n"); 191 return -ENODEV; 192 } 193 194 pc->mmio_base = devm_request_and_ioremap(&pdev->dev, r); 195 if (!pc->mmio_base) 196 return -EADDRNOTAVAIL; 197 198 ret = pwmchip_add(&pc->chip); 199 if (ret < 0) { 200 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); 201 return ret; 202 } 203 204 pm_runtime_enable(&pdev->dev); 205 platform_set_drvdata(pdev, pc); 206 return 0; 207 } 208 209 static int __devexit ecap_pwm_remove(struct platform_device *pdev) 210 { 211 struct ecap_pwm_chip *pc = platform_get_drvdata(pdev); 212 213 pm_runtime_put_sync(&pdev->dev); 214 pm_runtime_disable(&pdev->dev); 215 return pwmchip_remove(&pc->chip); 216 } 217 218 static struct platform_driver ecap_pwm_driver = { 219 .driver = { 220 .name = "ecap", 221 }, 222 .probe = ecap_pwm_probe, 223 .remove = __devexit_p(ecap_pwm_remove), 224 }; 225 226 module_platform_driver(ecap_pwm_driver); 227 228 MODULE_DESCRIPTION("ECAP PWM driver"); 229 MODULE_AUTHOR("Texas Instruments"); 230 MODULE_LICENSE("GPL"); 231