161 lines
3.6 KiB
C
161 lines
3.6 KiB
C
/*
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* linux/arch/unicore32/kernel/pwm.c
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*
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* Code specific to PKUnity SoC and UniCore ISA
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*
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* Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
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* Copyright (C) 2001-2010 Guan Xuetao
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/pwm.h>
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#include <asm/div64.h>
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#include <mach/hardware.h>
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struct puv3_pwm_chip {
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struct pwm_chip chip;
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void __iomem *base;
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struct clk *clk;
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};
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static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
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{
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return container_of(chip, struct puv3_pwm_chip, chip);
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}
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/*
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* period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
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* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
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*/
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static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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unsigned long period_cycles, prescale, pv, dc;
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struct puv3_pwm_chip *puv3 = to_puv3(chip);
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unsigned long long c;
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c = clk_get_rate(puv3->clk);
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c = c * period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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if (period_cycles < 1)
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period_cycles = 1;
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prescale = (period_cycles - 1) / 1024;
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pv = period_cycles / (prescale + 1) - 1;
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if (prescale > 63)
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return -EINVAL;
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if (duty_ns == period_ns)
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dc = OST_PWMDCCR_FDCYCLE;
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else
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dc = (pv + 1) * duty_ns / period_ns;
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/*
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* NOTE: the clock to PWM has to be enabled first
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* before writing to the registers
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*/
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clk_prepare_enable(puv3->clk);
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writel(prescale, puv3->base + OST_PWM_PWCR);
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writel(pv - dc, puv3->base + OST_PWM_DCCR);
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writel(pv, puv3->base + OST_PWM_PCR);
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clk_disable_unprepare(puv3->clk);
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return 0;
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}
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static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct puv3_pwm_chip *puv3 = to_puv3(chip);
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return clk_prepare_enable(puv3->clk);
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}
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static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct puv3_pwm_chip *puv3 = to_puv3(chip);
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clk_disable_unprepare(puv3->clk);
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}
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static const struct pwm_ops puv3_pwm_ops = {
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.config = puv3_pwm_config,
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.enable = puv3_pwm_enable,
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.disable = puv3_pwm_disable,
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.owner = THIS_MODULE,
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};
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static int pwm_probe(struct platform_device *pdev)
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{
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struct puv3_pwm_chip *puv3;
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struct resource *r;
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int ret;
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puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
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if (puv3 == NULL) {
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dev_err(&pdev->dev, "failed to allocate memory\n");
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return -ENOMEM;
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}
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puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
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if (IS_ERR(puv3->clk))
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return PTR_ERR(puv3->clk);
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (r == NULL) {
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dev_err(&pdev->dev, "no memory resource defined\n");
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return -ENODEV;
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}
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puv3->base = devm_ioremap_resource(&pdev->dev, r);
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if (IS_ERR(puv3->base))
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return PTR_ERR(puv3->base);
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puv3->chip.dev = &pdev->dev;
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puv3->chip.ops = &puv3_pwm_ops;
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puv3->chip.base = -1;
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puv3->chip.npwm = 1;
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ret = pwmchip_add(&puv3->chip);
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if (ret < 0) {
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dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
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return ret;
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}
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platform_set_drvdata(pdev, puv3);
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return 0;
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}
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static int pwm_remove(struct platform_device *pdev)
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{
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struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
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return pwmchip_remove(&puv3->chip);
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}
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static struct platform_driver puv3_pwm_driver = {
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.driver = {
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.name = "PKUnity-v3-PWM",
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},
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.probe = pwm_probe,
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.remove = pwm_remove,
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};
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module_platform_driver(puv3_pwm_driver);
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MODULE_LICENSE("GPL v2");
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