Version: v4.11.2

linux/drivers/pwm/pwm-vt8500.c

    1 
    2 
    3 
    4 
    5 
    6 
    7 
    8 
    9 
   10 
   11 
   12 
   13 
   14 
   15 
   16 
   17 
   18 
   19 
   20 
   21 
   22 
   23 
   24 
   25 
   26 
   27 
   28 
   29 
   30 
   31 
   32 
   33 
   34 
   35 
   36 
   37 
   38 
   39 
   40 
   41 
   42 
   43 
   44 
   45 
   46 
   47 
   48 
   49 
   50 
   51 
   52 
   53 
   54 
   55 
   56 
   57 
   58 
   59 
   60 
   61 
   62 
   63 
   64 
   65 
   66 
   67 
   68 
   69 
   70 
   71 
   72 
   73 
   74 
   75 
   76 
   77 
   78 
   79 
   80 
   81 
   82 
   83 
   84 
   85 
   86 
   87 
   88 
   89 
   90 
   91 
   92 
   93 
   94 
   95 
   96 
   97 
   98 
   99 
  100 
  101 
  102 
  103 
  104 
  105 
  106 
  107 
  108 
  109 
  110 
  111 
  112 
  113 
  114 
  115 
  116 
  117 
  118 
  119 
  120 
  121 
  122 
  123 
  124 
  125 
  126 
  127 
  128 
  129 
  130 
  131 
  132 
  133 
  134 
  135 
  136 
  137 
  138 
  139 
  140 
  141 
  142 
  143 
  144 
  145 
  146 
  147 
  148 
  149 
  150 
  151 
  152 
  153 
  154 
  155 
  156 
  157 
  158 
  159 
  160 
  161 
  162 
  163 
  164 
  165 
  166 
  167 
  168 
  169 
  170 
  171 
  172 
  173 
  174 
  175 
  176 
  177 
  178 
  179 
  180 
  181 
  182 
  183 
  184 
  185 
  186 
  187 
  188 
  189 
  190 
  191 
  192 
  193 
  194 
  195 
  196 
  197 
  198 
  199 
  200 
  201 
  202 
  203 
  204 
  205 
  206 
  207 
  208 
  209 
  210 
  211 
  212 
  213 
  214 
  215 
  216 
  217 
  218 
  219 
  220 
  221 
  222 
  223 
  224 
  225 
  226 
  227 
  228 
  229 
  230 
  231 
  232 
  233 
  234 
  235 
  236 
  237 
  238 
  239 
  240 
  241 
  242 
  243 
  244 
  245 
  246 
  247 
  248 
  249 
  250 
  251 
  252 
  253 
  254 
  255 
  256 
  257 
  258 
  259 
  260 
  261 
  262 
  263 
  264 
  265 
  266 
  267 
  268 
  269 
  270 
  271 
  272 
  273 
  274 
  275 
  276 
/*
 * drivers/pwm/pwm-vt8500.c
 *
 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <linux/delay.h>
#include <linux/clk.h>

#include <asm/div64.h>

#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_address.h>

/*
 * SoC architecture allocates register space for 4 PWMs but only
 * 2 are currently implemented.
 */
#define VT8500_NR_PWMS	2

#define REG_CTRL(pwm)		(((pwm) << 4) + 0x00)
#define REG_SCALAR(pwm)		(((pwm) << 4) + 0x04)
#define REG_PERIOD(pwm)		(((pwm) << 4) + 0x08)
#define REG_DUTY(pwm)		(((pwm) << 4) + 0x0C)
#define REG_STATUS		0x40

#define CTRL_ENABLE		BIT(0)
#define CTRL_INVERT		BIT(1)
#define CTRL_AUTOLOAD		BIT(2)
#define CTRL_STOP_IMM		BIT(3)
#define CTRL_LOAD_PRESCALE	BIT(4)
#define CTRL_LOAD_PERIOD	BIT(5)

#define STATUS_CTRL_UPDATE	BIT(0)
#define STATUS_SCALAR_UPDATE	BIT(1)
#define STATUS_PERIOD_UPDATE	BIT(2)
#define STATUS_DUTY_UPDATE	BIT(3)
#define STATUS_ALL_UPDATE	0x0F

struct vt8500_chip {
	struct pwm_chip chip;
	void __iomem *base;
	struct clk *clk;
};

#define to_vt8500_chip(chip)	container_of(chip, struct vt8500_chip, chip)

#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
{
	int loops = msecs_to_loops(10);
	u32 mask = bitmask << (nr << 8);

	while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
		cpu_relax();

	if (unlikely(!loops))
		dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n",
			 mask);
}

static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
		int duty_ns, int period_ns)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	unsigned long long c;
	unsigned long period_cycles, prescale, pv, dc;
	int err;
	u32 val;

	err = clk_enable(vt8500->clk);
	if (err < 0) {
		dev_err(chip->dev, "failed to enable clock\n");
		return err;
	}

	c = clk_get_rate(vt8500->clk);
	c = c * period_ns;
	do_div(c, 1000000000);
	period_cycles = c;

	if (period_cycles < 1)
		period_cycles = 1;
	prescale = (period_cycles - 1) / 4096;
	pv = period_cycles / (prescale + 1) - 1;
	if (pv > 4095)
		pv = 4095;

	if (prescale > 1023) {
		clk_disable(vt8500->clk);
		return -EINVAL;
	}

	c = (unsigned long long)pv * duty_ns;
	do_div(c, period_ns);
	dc = c;

	writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);

	writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);

	writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
	val |= CTRL_AUTOLOAD;
	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	clk_disable(vt8500->clk);
	return 0;
}

static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	int err;
	u32 val;

	err = clk_enable(vt8500->clk);
	if (err < 0) {
		dev_err(chip->dev, "failed to enable clock\n");
		return err;
	}

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
	val |= CTRL_ENABLE;
	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	return 0;
}

static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	u32 val;

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
	val &= ~CTRL_ENABLE;
	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	clk_disable(vt8500->clk);
}

static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
				   struct pwm_device *pwm,
				   enum pwm_polarity polarity)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	u32 val;

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));

	if (polarity == PWM_POLARITY_INVERSED)
		val |= CTRL_INVERT;
	else
		val &= ~CTRL_INVERT;

	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	return 0;
}

static const struct pwm_ops vt8500_pwm_ops = {
	.enable = vt8500_pwm_enable,
	.disable = vt8500_pwm_disable,
	.config = vt8500_pwm_config,
	.set_polarity = vt8500_pwm_set_polarity,
	.owner = THIS_MODULE,
};

static const struct of_device_id vt8500_pwm_dt_ids[] = {
	{ .compatible = "via,vt8500-pwm", },
	{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);

static int vt8500_pwm_probe(struct platform_device *pdev)
{
	struct vt8500_chip *chip;
	struct resource *r;
	struct device_node *np = pdev->dev.of_node;
	int ret;

	if (!np) {
		dev_err(&pdev->dev, "invalid devicetree node\n");
		return -EINVAL;
	}

	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
	if (chip == NULL)
		return -ENOMEM;

	chip->chip.dev = &pdev->dev;
	chip->chip.ops = &vt8500_pwm_ops;
	chip->chip.of_xlate = of_pwm_xlate_with_flags;
	chip->chip.of_pwm_n_cells = 3;
	chip->chip.base = -1;
	chip->chip.npwm = VT8500_NR_PWMS;

	chip->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(chip->clk)) {
		dev_err(&pdev->dev, "clock source not specified\n");
		return PTR_ERR(chip->clk);
	}

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	chip->base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(chip->base))
		return PTR_ERR(chip->base);

	ret = clk_prepare(chip->clk);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to prepare clock\n");
		return ret;
	}

	ret = pwmchip_add(&chip->chip);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to add PWM chip\n");
		return ret;
	}

	platform_set_drvdata(pdev, chip);
	return ret;
}

static int vt8500_pwm_remove(struct platform_device *pdev)
{
	struct vt8500_chip *chip;

	chip = platform_get_drvdata(pdev);
	if (chip == NULL)
		return -ENODEV;

	clk_unprepare(chip->clk);

	return pwmchip_remove(&chip->chip);
}

static struct platform_driver vt8500_pwm_driver = {
	.probe		= vt8500_pwm_probe,
	.remove		= vt8500_pwm_remove,
	.driver		= {
		.name	= "vt8500-pwm",
		.of_match_table = vt8500_pwm_dt_ids,
	},
};
module_platform_driver(vt8500_pwm_driver);

MODULE_DESCRIPTION("VT8500 PWM Driver");
MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
MODULE_LICENSE("GPL v2");

This page was automatically generated by Elixir 0.1.2 (source)  •  Please report bugs by mail or directly through the issue tracker.