263 lines
6.3 KiB
C
263 lines
6.3 KiB
C
/*
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* simple driver for PWM (Pulse Width Modulator) controller
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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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* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
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*/
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#include <common.h>
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#include <init.h>
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#include <errno.h>
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#include <io.h>
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#include <pwm.h>
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#include <linux/clk.h>
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#include <asm-generic/div64.h>
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/* i.MX1 and i.MX21 share the same PWM function block: */
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#define MX1_PWMC 0x00 /* PWM Control Register */
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#define MX1_PWMS 0x04 /* PWM Sample Register */
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#define MX1_PWMP 0x08 /* PWM Period Register */
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#define MX1_PWMC_EN (1 << 4)
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/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
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#define MX3_PWMCR 0x00 /* PWM Control Register */
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#define MX3_PWMSAR 0x0C /* PWM Sample Register */
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#define MX3_PWMPR 0x10 /* PWM Period Register */
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#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
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#define MX3_PWMCR_DOZEEN (1 << 24)
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#define MX3_PWMCR_WAITEN (1 << 23)
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#define MX3_PWMCR_DBGEN (1 << 22)
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#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
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#define MX3_PWMCR_CLKSRC_IPG (1 << 16)
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#define MX3_PWMCR_EN (1 << 0)
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struct imx_chip {
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struct clk *clk_per;
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void __iomem *mmio_base;
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struct pwm_chip chip;
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int (*config)(struct pwm_chip *chip,
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int duty_ns, int period_ns);
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void (*set_enable)(struct pwm_chip *chip, bool enable);
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};
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#define to_imx_chip(chip) container_of(chip, struct imx_chip, chip)
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static int imx_pwm_config_v1(struct pwm_chip *chip,
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int duty_ns, int period_ns)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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/*
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* The PWM subsystem allows for exact frequencies. However,
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* I cannot connect a scope on my device to the PWM line and
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* thus cannot provide the program the PWM controller
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* exactly. Instead, I'm relying on the fact that the
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* Bootloader (u-boot or WinCE+haret) has programmed the PWM
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* function group already. So I'll just modify the PWM sample
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* register to follow the ratio of duty_ns vs. period_ns
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* accordingly.
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*
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* This is good enough for programming the brightness of
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* the LCD backlight.
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*
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* The real implementation would divide PERCLK[0] first by
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* both the prescaler (/1 .. /128) and then by CLKSEL
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* (/2 .. /16).
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*/
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u32 max = readl(imx->mmio_base + MX1_PWMP);
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u32 p = max * duty_ns / period_ns;
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writel(max - p, imx->mmio_base + MX1_PWMS);
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return 0;
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}
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static void imx_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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u32 val;
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val = readl(imx->mmio_base + MX1_PWMC);
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if (enable)
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val |= MX1_PWMC_EN;
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else
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val &= ~MX1_PWMC_EN;
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writel(val, imx->mmio_base + MX1_PWMC);
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}
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static int imx_pwm_config_v2(struct pwm_chip *chip,
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int duty_ns, int period_ns)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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unsigned long long c;
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unsigned long period_cycles, duty_cycles, prescale;
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u32 cr;
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c = clk_get_rate(imx->clk_per);
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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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prescale = period_cycles / 0x10000 + 1;
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period_cycles /= prescale;
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c = (unsigned long long)period_cycles * duty_ns;
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do_div(c, period_ns);
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duty_cycles = c;
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/*
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* according to imx pwm RM, the real period value should be
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* PERIOD value in PWMPR plus 2.
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*/
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if (period_cycles > 2)
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period_cycles -= 2;
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else
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period_cycles = 0;
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writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
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writel(period_cycles, imx->mmio_base + MX3_PWMPR);
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cr = MX3_PWMCR_PRESCALER(prescale) |
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MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
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MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
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if (readl(imx->mmio_base + MX3_PWMCR) & MX3_PWMCR_EN)
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cr |= MX3_PWMCR_EN;
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writel(cr, imx->mmio_base + MX3_PWMCR);
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return 0;
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}
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static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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u32 val;
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val = readl(imx->mmio_base + MX3_PWMCR);
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if (enable)
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val |= MX3_PWMCR_EN;
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else
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val &= ~MX3_PWMCR_EN;
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writel(val, imx->mmio_base + MX3_PWMCR);
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}
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static int imx_pwm_config(struct pwm_chip *chip,
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int duty_ns, int period_ns)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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int ret;
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ret = imx->config(chip, duty_ns, period_ns);
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return ret;
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}
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static int imx_pwm_enable(struct pwm_chip *chip)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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imx->set_enable(chip, true);
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return 0;
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}
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static void imx_pwm_disable(struct pwm_chip *chip)
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{
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struct imx_chip *imx = to_imx_chip(chip);
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imx->set_enable(chip, false);
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}
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static struct pwm_ops imx_pwm_ops = {
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.enable = imx_pwm_enable,
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.disable = imx_pwm_disable,
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.config = imx_pwm_config,
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};
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struct imx_pwm_data {
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int (*config)(struct pwm_chip *chip,
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int duty_ns, int period_ns);
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void (*set_enable)(struct pwm_chip *chip, bool enable);
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};
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static struct imx_pwm_data imx_pwm_data_v1 = {
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.config = imx_pwm_config_v1,
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.set_enable = imx_pwm_set_enable_v1,
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};
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static struct imx_pwm_data imx_pwm_data_v2 = {
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.config = imx_pwm_config_v2,
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.set_enable = imx_pwm_set_enable_v2,
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};
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static struct of_device_id imx_pwm_dt_ids[] = {
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{ .compatible = "fsl,imx1-pwm", .data = (unsigned long)&imx_pwm_data_v1, },
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{ .compatible = "fsl,imx27-pwm", .data = (unsigned long)&imx_pwm_data_v2, },
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{ /* sentinel */ }
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};
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static int imx_pwm_probe(struct device_d *dev)
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{
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const struct imx_pwm_data *data;
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struct imx_chip *imx;
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int ret = 0;
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ret = dev_get_drvdata(dev, (unsigned long *)&data);
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if (ret)
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return ret;
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imx = xzalloc(sizeof(*imx));
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imx->clk_per = clk_get(dev, "per");
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if (IS_ERR(imx->clk_per))
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return PTR_ERR(imx->clk_per);
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imx->chip.ops = &imx_pwm_ops;
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if (dev->device_node) {
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imx->chip.devname = of_alias_get(dev->device_node);
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if (!imx->chip.devname) {
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dev_err(dev, "no alias for pwm\n");
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return -EINVAL;
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}
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} else {
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imx->chip.devname = asprintf("pwm%d", dev->id);
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}
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imx->mmio_base = dev_request_mem_region(dev, 0);
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if (!imx->mmio_base)
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return -EBUSY;
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imx->config = data->config;
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imx->set_enable = data->set_enable;
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ret = pwmchip_add(&imx->chip, dev);
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if (ret < 0)
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return ret;
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return 0;
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}
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static struct driver_d imx_pwm_driver = {
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.name = "imx-pwm",
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.of_compatible = imx_pwm_dt_ids,
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.probe = imx_pwm_probe,
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};
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coredevice_platform_driver(imx_pwm_driver);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
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