350 lines
8.6 KiB
C
350 lines
8.6 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 <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/delay.h>
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#include <linux/io.h>
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#include <linux/pwm.h>
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#include <linux/of.h>
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#include <linux/of_device.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_PWMSR 0x04 /* PWM Status 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_SWR (1 << 3)
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#define MX3_PWMCR_EN (1 << 0)
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#define MX3_PWMSR_FIFOAV_4WORDS 0x4
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#define MX3_PWMSR_FIFOAV_MASK 0x7
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#define MX3_PWM_SWR_LOOP 5
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struct imx_chip {
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struct clk *clk_per;
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struct clk *clk_ipg;
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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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struct pwm_device *pwm, 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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struct pwm_device *pwm, 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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struct pwm_device *pwm, 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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struct device *dev = chip->dev;
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unsigned long long c;
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unsigned long period_cycles, duty_cycles, prescale;
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unsigned int period_ms;
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bool enable = pwm_is_enabled(pwm);
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int wait_count = 0, fifoav;
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u32 cr, sr;
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/*
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* i.MX PWMv2 has a 4-word sample FIFO.
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* In order to avoid FIFO overflow issue, we do software reset
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* to clear all sample FIFO if the controller is disabled or
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* wait for a full PWM cycle to get a relinquished FIFO slot
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* when the controller is enabled and the FIFO is fully loaded.
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*/
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if (enable) {
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sr = readl(imx->mmio_base + MX3_PWMSR);
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fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
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if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
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period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
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NSEC_PER_MSEC);
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msleep(period_ms);
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sr = readl(imx->mmio_base + MX3_PWMSR);
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if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
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dev_warn(dev, "there is no free FIFO slot\n");
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}
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} else {
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writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
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do {
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usleep_range(200, 1000);
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cr = readl(imx->mmio_base + MX3_PWMCR);
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} while ((cr & MX3_PWMCR_SWR) &&
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(wait_count++ < MX3_PWM_SWR_LOOP));
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if (cr & MX3_PWMCR_SWR)
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dev_warn(dev, "software reset timeout\n");
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}
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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 (enable)
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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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struct pwm_device *pwm, 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 = clk_prepare_enable(imx->clk_ipg);
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if (ret)
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return ret;
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ret = imx->config(chip, pwm, duty_ns, period_ns);
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clk_disable_unprepare(imx->clk_ipg);
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return ret;
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}
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static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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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 = clk_prepare_enable(imx->clk_per);
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if (ret)
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return ret;
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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, struct pwm_device *pwm)
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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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clk_disable_unprepare(imx->clk_per);
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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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.owner = THIS_MODULE,
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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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struct pwm_device *pwm, 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 const struct of_device_id imx_pwm_dt_ids[] = {
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{ .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
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{ .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);
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static int imx_pwm_probe(struct platform_device *pdev)
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{
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const struct of_device_id *of_id =
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of_match_device(imx_pwm_dt_ids, &pdev->dev);
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const struct imx_pwm_data *data;
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struct imx_chip *imx;
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struct resource *r;
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int ret = 0;
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if (!of_id)
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return -ENODEV;
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imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
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if (imx == NULL)
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return -ENOMEM;
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imx->clk_per = devm_clk_get(&pdev->dev, "per");
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if (IS_ERR(imx->clk_per)) {
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dev_err(&pdev->dev, "getting per clock failed with %ld\n",
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PTR_ERR(imx->clk_per));
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return PTR_ERR(imx->clk_per);
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}
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imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
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if (IS_ERR(imx->clk_ipg)) {
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dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
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PTR_ERR(imx->clk_ipg));
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return PTR_ERR(imx->clk_ipg);
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}
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imx->chip.ops = &imx_pwm_ops;
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imx->chip.dev = &pdev->dev;
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imx->chip.base = -1;
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imx->chip.npwm = 1;
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imx->chip.can_sleep = true;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
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if (IS_ERR(imx->mmio_base))
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return PTR_ERR(imx->mmio_base);
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data = of_id->data;
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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);
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if (ret < 0)
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return ret;
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platform_set_drvdata(pdev, imx);
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return 0;
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}
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static int imx_pwm_remove(struct platform_device *pdev)
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{
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struct imx_chip *imx;
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imx = platform_get_drvdata(pdev);
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if (imx == NULL)
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return -ENODEV;
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return pwmchip_remove(&imx->chip);
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}
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static struct platform_driver imx_pwm_driver = {
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.driver = {
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.name = "imx-pwm",
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.of_match_table = imx_pwm_dt_ids,
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},
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.probe = imx_pwm_probe,
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.remove = imx_pwm_remove,
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};
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module_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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