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![Fabio Estevam](/assets/img/avatar_default.png)
On a imx6q-cubox-i board, which has an LED driven by PWM, when the system goes into suspend the PWM block is disabled by default, then the PWM pin goes to logic level zero and turn on the LED during suspend, which is not really the behaviour we want to see. By keeping the PWM enabled during suspend via STOPEN bit, the pwm-leds driver sets the brightness to zero in suspend and then the LED is turned off as expected. So always set the STOPEN to fix the PWM behaviour in suspend. Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
336 lines
8.2 KiB
C
336 lines
8.2 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_STOPEN (1 << 25)
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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_POUTC (1 << 18)
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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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void __iomem *mmio_base;
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struct pwm_chip chip;
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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 int imx_pwm_enable_v1(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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u32 val;
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int ret;
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ret = clk_prepare_enable(imx->clk_per);
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if (ret < 0)
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return ret;
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val = readl(imx->mmio_base + MX1_PWMC);
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val |= MX1_PWMC_EN;
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writel(val, imx->mmio_base + MX1_PWMC);
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return 0;
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}
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static void imx_pwm_disable_v1(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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u32 val;
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val = readl(imx->mmio_base + MX1_PWMC);
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val &= ~MX1_PWMC_EN;
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writel(val, imx->mmio_base + MX1_PWMC);
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clk_disable_unprepare(imx->clk_per);
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}
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static void imx_pwm_sw_reset(struct pwm_chip *chip)
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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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int wait_count = 0;
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u32 cr;
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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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static void imx_pwm_wait_fifo_slot(struct pwm_chip *chip,
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struct pwm_device *pwm)
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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 int period_ms;
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int fifoav;
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u32 sr;
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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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}
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static int imx_pwm_apply_v2(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state)
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{
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unsigned long period_cycles, duty_cycles, prescale;
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struct imx_chip *imx = to_imx_chip(chip);
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struct pwm_state cstate;
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unsigned long long c;
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int ret;
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u32 cr;
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pwm_get_state(pwm, &cstate);
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if (state->enabled) {
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c = clk_get_rate(imx->clk_per);
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c *= state->period;
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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 * state->duty_cycle;
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do_div(c, state->period);
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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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/*
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* Wait for a free FIFO slot if the PWM is already enabled, and
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* flush the FIFO if the PWM was disabled and is about to be
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* enabled.
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*/
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if (cstate.enabled) {
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imx_pwm_wait_fifo_slot(chip, pwm);
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} else {
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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_pwm_sw_reset(chip);
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}
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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_STOPEN | MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
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MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH |
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MX3_PWMCR_EN;
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if (state->polarity == PWM_POLARITY_INVERSED)
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cr |= MX3_PWMCR_POUTC;
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writel(cr, imx->mmio_base + MX3_PWMCR);
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} else if (cstate.enabled) {
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writel(0, imx->mmio_base + MX3_PWMCR);
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clk_disable_unprepare(imx->clk_per);
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}
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return 0;
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}
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static const struct pwm_ops imx_pwm_ops_v1 = {
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.enable = imx_pwm_enable_v1,
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.disable = imx_pwm_disable_v1,
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.config = imx_pwm_config_v1,
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.owner = THIS_MODULE,
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};
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static const struct pwm_ops imx_pwm_ops_v2 = {
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.apply = imx_pwm_apply_v2,
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.owner = THIS_MODULE,
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};
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struct imx_pwm_data {
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bool polarity_supported;
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const struct pwm_ops *ops;
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};
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static struct imx_pwm_data imx_pwm_data_v1 = {
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.ops = &imx_pwm_ops_v1,
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};
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static struct imx_pwm_data imx_pwm_data_v2 = {
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.polarity_supported = true,
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.ops = &imx_pwm_ops_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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data = of_id->data;
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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->chip.ops = data->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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if (data->polarity_supported) {
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dev_dbg(&pdev->dev, "PWM supports output inversion\n");
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imx->chip.of_xlate = of_pwm_xlate_with_flags;
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imx->chip.of_pwm_n_cells = 3;
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}
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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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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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