diff options
Diffstat (limited to 'drivers/pwm/pwm-imx.c')
| -rw-r--r-- | drivers/pwm/pwm-imx.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c new file mode 100644 index 00000000000..2a0b3533397 --- /dev/null +++ b/drivers/pwm/pwm-imx.c @@ -0,0 +1,230 @@ +/* + * simple driver for PWM (Pulse Width Modulator) controller + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/pwm.h> +#include <mach/hardware.h> + + +/* i.MX1 and i.MX21 share the same PWM function block: */ + +#define MX1_PWMC 0x00 /* PWM Control Register */ +#define MX1_PWMS 0x04 /* PWM Sample Register */ +#define MX1_PWMP 0x08 /* PWM Period Register */ + + +/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */ + +#define MX3_PWMCR 0x00 /* PWM Control Register */ +#define MX3_PWMSAR 0x0C /* PWM Sample Register */ +#define MX3_PWMPR 0x10 /* PWM Period Register */ +#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4) +#define MX3_PWMCR_DOZEEN (1 << 24) +#define MX3_PWMCR_WAITEN (1 << 23) +#define MX3_PWMCR_DBGEN (1 << 22) +#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) +#define MX3_PWMCR_CLKSRC_IPG (1 << 16) +#define MX3_PWMCR_EN (1 << 0) + +struct imx_chip { + struct clk *clk; + + int clk_enabled; + void __iomem *mmio_base; + + struct pwm_chip chip; +}; + +#define to_imx_chip(chip) container_of(chip, struct imx_chip, chip) + +static int imx_pwm_config(struct pwm_chip *chip, + struct pwm_device *pwm, int duty_ns, int period_ns) +{ + struct imx_chip *imx = to_imx_chip(chip); + + if (!(cpu_is_mx1() || cpu_is_mx21())) { + unsigned long long c; + unsigned long period_cycles, duty_cycles, prescale; + u32 cr; + + c = clk_get_rate(imx->clk); + c = c * period_ns; + do_div(c, 1000000000); + period_cycles = c; + + prescale = period_cycles / 0x10000 + 1; + + period_cycles /= prescale; + c = (unsigned long long)period_cycles * duty_ns; + do_div(c, period_ns); + duty_cycles = c; + + /* + * according to imx pwm RM, the real period value should be + * PERIOD value in PWMPR plus 2. + */ + if (period_cycles > 2) + period_cycles -= 2; + else + period_cycles = 0; + + writel(duty_cycles, imx->mmio_base + MX3_PWMSAR); + writel(period_cycles, imx->mmio_base + MX3_PWMPR); + + cr = MX3_PWMCR_PRESCALER(prescale) | + MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN | + MX3_PWMCR_DBGEN | MX3_PWMCR_EN; + + if (cpu_is_mx25()) + cr |= MX3_PWMCR_CLKSRC_IPG; + else + cr |= MX3_PWMCR_CLKSRC_IPG_HIGH; + + writel(cr, imx->mmio_base + MX3_PWMCR); + } else if (cpu_is_mx1() || cpu_is_mx21()) { + /* The PWM subsystem allows for exact frequencies. However, + * I cannot connect a scope on my device to the PWM line and + * thus cannot provide the program the PWM controller + * exactly. Instead, I'm relying on the fact that the + * Bootloader (u-boot or WinCE+haret) has programmed the PWM + * function group already. So I'll just modify the PWM sample + * register to follow the ratio of duty_ns vs. period_ns + * accordingly. + * + * This is good enough for programming the brightness of + * the LCD backlight. + * + * The real implementation would divide PERCLK[0] first by + * both the prescaler (/1 .. /128) and then by CLKSEL + * (/2 .. /16). + */ + u32 max = readl(imx->mmio_base + MX1_PWMP); + u32 p = max * duty_ns / period_ns; + writel(max - p, imx->mmio_base + MX1_PWMS); + } else { + BUG(); + } + + return 0; +} + +static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct imx_chip *imx = to_imx_chip(chip); + int rc = 0; + + if (!imx->clk_enabled) { + rc = clk_prepare_enable(imx->clk); + if (!rc) + imx->clk_enabled = 1; + } + return rc; +} + +static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct imx_chip *imx = to_imx_chip(chip); + + writel(0, imx->mmio_base + MX3_PWMCR); + + if (imx->clk_enabled) { + clk_disable_unprepare(imx->clk); + imx->clk_enabled = 0; + } +} + +static struct pwm_ops imx_pwm_ops = { + .enable = imx_pwm_enable, + .disable = imx_pwm_disable, + .config = imx_pwm_config, + .owner = THIS_MODULE, +}; + +static int __devinit imx_pwm_probe(struct platform_device *pdev) +{ + struct imx_chip *imx; + struct resource *r; + int ret = 0; + + imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); + if (imx == NULL) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + imx->clk = devm_clk_get(&pdev->dev, "pwm"); + + if (IS_ERR(imx->clk)) + return PTR_ERR(imx->clk); + + imx->chip.ops = &imx_pwm_ops; + imx->chip.dev = &pdev->dev; + imx->chip.base = -1; + imx->chip.npwm = 1; + + imx->clk_enabled = 0; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (r == NULL) { + dev_err(&pdev->dev, "no memory resource defined\n"); + return -ENODEV; + } + + imx->mmio_base = devm_request_and_ioremap(&pdev->dev, r); + if (imx->mmio_base == NULL) + return -EADDRNOTAVAIL; + + ret = pwmchip_add(&imx->chip); + if (ret < 0) + return ret; + + platform_set_drvdata(pdev, imx); + return 0; +} + +static int __devexit imx_pwm_remove(struct platform_device *pdev) +{ + struct imx_chip *imx; + + imx = platform_get_drvdata(pdev); + if (imx == NULL) + return -ENODEV; + + return pwmchip_remove(&imx->chip); +} + +static struct platform_driver imx_pwm_driver = { + .driver = { + .name = "mxc_pwm", + }, + .probe = imx_pwm_probe, + .remove = __devexit_p(imx_pwm_remove), +}; + +static int __init imx_pwm_init(void) +{ + return platform_driver_register(&imx_pwm_driver); +} +arch_initcall(imx_pwm_init); + +static void __exit imx_pwm_exit(void) +{ + platform_driver_unregister(&imx_pwm_driver); +} +module_exit(imx_pwm_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); |