drivers/pwm/pwm-pxa.c

   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/mod_devicetable.h>
  19 #include <linux/module.h>
  20 #include <linux/kernel.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/slab.h>
  23 #include <linux/err.h>
  24 #include <linux/clk.h>
  25 #include <linux/io.h>
  26 #include <linux/pwm.h>
  27 #include <linux/of.h>
  28
  29 #include <asm/div64.h>
  30
  31 #define HAS_SECONDARY_PWM       0x10
  32
  33 static const struct platform_device_id pwm_id_table[] = {
  34         /*   PWM    has_secondary_pwm? */
  35         { "pxa25x-pwm", 0 },
  36         { "pxa27x-pwm", HAS_SECONDARY_PWM },
  37         { "pxa168-pwm", 0 },
  38         { "pxa910-pwm", 0 },
  39         { },
  40 };
  41 MODULE_DEVICE_TABLE(platform, pwm_id_table);
  42
  43 /* PWM registers and bits definitions */
  44 #define PWMCR           (0x00)
  45 #define PWMDCR          (0x04)
  46 #define PWMPCR          (0x08)
  47
  48 #define PWMCR_SD        (1 << 6)
  49 #define PWMDCR_FD       (1 << 10)
  50
  51 struct pxa_pwm_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 pwmchip_get_drvdata(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 };
 138
 139 #ifdef CONFIG_OF
 140 /*
 141  * Device tree users must create one device instance for each PWM channel.
 142  * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver
 143  * code that this is a single channel pxa25x-pwm.  Currently all devices are
 144  * supported identically.
 145  */
 146 static const struct of_device_id pwm_of_match[] = {
 147         { .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]},
 148         { .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]},
 149         { .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]},
 150         { .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]},
 151         { }
 152 };
 153 MODULE_DEVICE_TABLE(of, pwm_of_match);
 154 #else
 155 #define pwm_of_match NULL
 156 #endif
 157
 158 static int pwm_probe(struct platform_device *pdev)
 159 {
 160         const struct platform_device_id *id = platform_get_device_id(pdev);
 161         struct pwm_chip *chip;
 162         struct pxa_pwm_chip *pc;
 163         int ret = 0;
 164
 165         if (IS_ENABLED(CONFIG_OF) && id == NULL)
 166                 id = of_device_get_match_data(&pdev->dev);
 167
 168         if (id == NULL)
 169                 return -EINVAL;
 170
 171         chip = devm_pwmchip_alloc(&pdev->dev,
 172                                   (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1,
 173                                   sizeof(*pc));
 174         if (IS_ERR(chip))
 175                 return PTR_ERR(chip);
 176         pc = to_pxa_pwm_chip(chip);
 177
 178         pc->clk = devm_clk_get(&pdev->dev, NULL);
 179         if (IS_ERR(pc->clk))
 180                 return PTR_ERR(pc->clk);
 181
 182         chip->ops = &pxa_pwm_ops;
 183
 184         if (IS_ENABLED(CONFIG_OF))
 185                 chip->of_xlate = of_pwm_single_xlate;
 186
 187         pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
 188         if (IS_ERR(pc->mmio_base))
 189                 return PTR_ERR(pc->mmio_base);
 190
 191         ret = devm_pwmchip_add(&pdev->dev, chip);
 192         if (ret < 0) {
 193                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 194                 return ret;
 195         }
 196
 197         return 0;
 198 }
 199
 200 static struct platform_driver pwm_driver = {
 201         .driver         = {
 202                 .name   = "pxa25x-pwm",
 203                 .of_match_table = pwm_of_match,
 204         },
 205         .probe          = pwm_probe,
 206         .id_table       = pwm_id_table,
 207 };
 208
 209 module_platform_driver(pwm_driver);
 210
 211 MODULE_DESCRIPTION("PXA Pulse Width Modulator driver");
 212 MODULE_LICENSE("GPL v2");