1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * drivers/pwm/pwm-pxa.c 4 * 5 * simple driver for PWM (Pulse Width Modulator) controller 6 * 7 * 2008-02-13 initial version 8 * eric miao <eric.miao@marvell.com> 9 * 10 * Links to reference manuals for some of the supported PWM chips can be found 11 * in Documentation/arch/arm/marvell.rst. 12 * 13 * Limitations: 14 * - When PWM is stopped, the current PWM period stops abruptly at the next 15 * input clock (PWMCR_SD is set) and the output is driven to inactive. 16 */ 17 18 #include <linux/module.h> 19 #include <linux/kernel.h> 20 #include <linux/platform_device.h> 21 #include <linux/slab.h> 22 #include <linux/err.h> 23 #include <linux/clk.h> 24 #include <linux/io.h> 25 #include <linux/pwm.h> 26 #include <linux/of_device.h> 27 28 #include <asm/div64.h> 29 30 #define HAS_SECONDARY_PWM 0x10 31 32 static const struct platform_device_id pwm_id_table[] = { 33 /* PWM has_secondary_pwm? */ 34 { "pxa25x-pwm", 0 }, 35 { "pxa27x-pwm", HAS_SECONDARY_PWM }, 36 { "pxa168-pwm", 0 }, 37 { "pxa910-pwm", 0 }, 38 { }, 39 }; 40 MODULE_DEVICE_TABLE(platform, pwm_id_table); 41 42 /* PWM registers and bits definitions */ 43 #define PWMCR (0x00) 44 #define PWMDCR (0x04) 45 #define PWMPCR (0x08) 46 47 #define PWMCR_SD (1 << 6) 48 #define PWMDCR_FD (1 << 10) 49 50 struct pxa_pwm_chip { 51 struct pwm_chip chip; 52 struct device *dev; 53 54 struct clk *clk; 55 void __iomem *mmio_base; 56 }; 57 58 static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip) 59 { 60 return container_of(chip, struct pxa_pwm_chip, chip); 61 } 62 63 /* 64 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE 65 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE 66 */ 67 static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 68 u64 duty_ns, u64 period_ns) 69 { 70 struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); 71 unsigned long long c; 72 unsigned long period_cycles, prescale, pv, dc; 73 unsigned long offset; 74 75 offset = pwm->hwpwm ? 0x10 : 0; 76 77 c = clk_get_rate(pc->clk); 78 c = c * period_ns; 79 do_div(c, 1000000000); 80 period_cycles = c; 81 82 if (period_cycles < 1) 83 period_cycles = 1; 84 prescale = (period_cycles - 1) / 1024; 85 pv = period_cycles / (prescale + 1) - 1; 86 87 if (prescale > 63) 88 return -EINVAL; 89 90 if (duty_ns == period_ns) 91 dc = PWMDCR_FD; 92 else 93 dc = mul_u64_u64_div_u64(pv + 1, duty_ns, period_ns); 94 95 writel(prescale | PWMCR_SD, pc->mmio_base + offset + PWMCR); 96 writel(dc, pc->mmio_base + offset + PWMDCR); 97 writel(pv, pc->mmio_base + offset + PWMPCR); 98 99 return 0; 100 } 101 102 static int pxa_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 103 const struct pwm_state *state) 104 { 105 struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); 106 u64 duty_cycle; 107 int err; 108 109 if (state->polarity != PWM_POLARITY_NORMAL) 110 return -EINVAL; 111 112 err = clk_prepare_enable(pc->clk); 113 if (err) 114 return err; 115 116 duty_cycle = state->enabled ? state->duty_cycle : 0; 117 118 err = pxa_pwm_config(chip, pwm, duty_cycle, state->period); 119 if (err) { 120 clk_disable_unprepare(pc->clk); 121 return err; 122 } 123 124 if (state->enabled && !pwm->state.enabled) 125 return 0; 126 127 clk_disable_unprepare(pc->clk); 128 129 if (!state->enabled && pwm->state.enabled) 130 clk_disable_unprepare(pc->clk); 131 132 return 0; 133 } 134 135 static const struct pwm_ops pxa_pwm_ops = { 136 .apply = pxa_pwm_apply, 137 .owner = THIS_MODULE, 138 }; 139 140 #ifdef CONFIG_OF 141 /* 142 * Device tree users must create one device instance for each PWM channel. 143 * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver 144 * code that this is a single channel pxa25x-pwm. Currently all devices are 145 * supported identically. 146 */ 147 static const struct of_device_id pwm_of_match[] = { 148 { .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]}, 149 { .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]}, 150 { .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]}, 151 { .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]}, 152 { } 153 }; 154 MODULE_DEVICE_TABLE(of, pwm_of_match); 155 #else 156 #define pwm_of_match NULL 157 #endif 158 159 static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev) 160 { 161 const struct of_device_id *id = of_match_device(pwm_of_match, dev); 162 163 return id ? id->data : NULL; 164 } 165 166 static int pwm_probe(struct platform_device *pdev) 167 { 168 const struct platform_device_id *id = platform_get_device_id(pdev); 169 struct pxa_pwm_chip *pc; 170 int ret = 0; 171 172 if (IS_ENABLED(CONFIG_OF) && id == NULL) 173 id = pxa_pwm_get_id_dt(&pdev->dev); 174 175 if (id == NULL) 176 return -EINVAL; 177 178 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); 179 if (pc == NULL) 180 return -ENOMEM; 181 182 pc->clk = devm_clk_get(&pdev->dev, NULL); 183 if (IS_ERR(pc->clk)) 184 return PTR_ERR(pc->clk); 185 186 pc->chip.dev = &pdev->dev; 187 pc->chip.ops = &pxa_pwm_ops; 188 pc->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1; 189 190 if (IS_ENABLED(CONFIG_OF)) { 191 pc->chip.of_xlate = of_pwm_single_xlate; 192 pc->chip.of_pwm_n_cells = 1; 193 } 194 195 pc->mmio_base = devm_platform_ioremap_resource(pdev, 0); 196 if (IS_ERR(pc->mmio_base)) 197 return PTR_ERR(pc->mmio_base); 198 199 ret = devm_pwmchip_add(&pdev->dev, &pc->chip); 200 if (ret < 0) { 201 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); 202 return ret; 203 } 204 205 return 0; 206 } 207 208 static struct platform_driver pwm_driver = { 209 .driver = { 210 .name = "pxa25x-pwm", 211 .of_match_table = pwm_of_match, 212 }, 213 .probe = pwm_probe, 214 .id_table = pwm_id_table, 215 }; 216 217 module_platform_driver(pwm_driver); 218 219 MODULE_LICENSE("GPL v2"); 220