On Wed, Nov 12, 2014 at 4:37 AM, <Naidu.Tellapati@xxxxxxxxxx> wrote:
> From: Naidu Tellapati <Naidu.Tellapati@xxxxxxxxxx>
>
> The Pistachio SOC from Imagination Technologies includes a Pulse Width
> Modulation DAC which produces 1 to 4 digital bit-outputs which represent
> digital waveforms. These PWM outputs are primarily in charge of controlling
> backlight LED devices.
>
> Signed-off-by: Naidu Tellapati <Naidu.Tellapati@xxxxxxxxxx>
> Signed-off-by: Sai Masarapu <Sai.Masarapu@xxxxxxxxxx>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index ef2dd2e..de1c922 100644
> @@ -110,6 +110,16 @@ config PWM_FSL_FTM
> To compile this driver as a module, choose M here: the module
> will be called pwm-fsl-ftm.
>
> +config PWM_IMG
> + tristate "Imagination Technologies PWM driver"
> + depends on MFD_SYSCON
It also at least depends on HAS_IOMEM. Is this IP present on non-MIPS
SoCs? If not, then maybe add depends on MIPS || COMPILE_TEST.
> diff --git a/drivers/pwm/pwm-img.c b/drivers/pwm/pwm-img.c
> new file mode 100755
> index 0000000..9361dbf
> @@ -0,0 +1,294 @@
> +/*
> + * Imagination Technologies Pulse Width Modulator driver
> + *
> + * Copyright (c) 2014, Imagination Technologies
> + *
> + * Based on drivers/pwm/pwm-tegra.c, Copyright (c) 2010, NVIDIA Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
I don't think this paragraph is necessary.
> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/mfd/syscon.h>
> +
> +/* PWM registers */
> +#define CR_PWM_CTRL_CFG 0x0000 /* Control and config register */
> +#define PWM_CH_DIV_MASK(ch) (BIT(ch * 2 + 4) | BIT(ch * 2 + 5))
This is a strange way to define a mask. Like I mentioned in the
watchdog driver, I prefer to use unshifted masks - not sure if Thierry
has a preference though.
Also, be sure to parenthesize macro parameters when they are used in
the expression.
> +#define PWM_CH_DIV_SHIFT(ch) (ch * 2 + 4)
> +
> +#define CR_PWM_CH_CFG(ch) (0x4 + (ch) * 4) /* Config register */
> +#define TMBASE_SHIFT 0
> +#define DUTY_SHIFT 16
Maybe prefix these tow CR_PWM_CH_CFG to make it clear as to which
register these fields belong? Same goes for the other field #defines
below.
> +#define CR_PERIP_PWM_PDM_CONTROL 0x0140 /* PWM and PDM ctrl register */
> +#define PWM_PDM_CH_CTRL_SHIFT(ch) (ch * 4)
> +
> +#define NUM_PWM 4
> +#define SUB_DIV0 1
> +#define SUB_DIV1 2
> +#define NO_SUB_DIV 0
> +#define SUB_DIV0_DIV1 3
> +#define MIN_TMBASE_STEPS 1
> +#define MAX_TMBASE_STEPS 65536
> +#define MIN_DUTY_STEPS 0
> +#define MAX_DUTY_STEPS 65535
Please place these #defines next to their corresponding register or
register field #define.
> +struct img_pwm_chip {
> + struct device *dev;
> + struct clk *clk;
> + struct pwm_chip chip;
> + void __iomem *base;
> + struct regmap *periph_regs;
> +};
> +
> +static inline struct img_pwm_chip *to_img_pwm_chip(struct pwm_chip *chip)
> +{
> + return container_of(chip, struct img_pwm_chip, chip);
> +}
> +
> +static inline void img_pwm_writel(struct img_pwm_chip *chip,
> + unsigned int reg, unsigned long val)
> +{
> + writel(val, chip->base + reg);
> +}
> +
> +static inline unsigned int img_pwm_readl(struct img_pwm_chip *chip,
> + unsigned int reg)
> +{
> + return readl(chip->base + reg);
> +}
> +
> +static int img_pwm_get_div_and_tmbase(struct pwm_chip *chip,
> + unsigned long in_freq, unsigned long out_freq,
> + unsigned int *divider, unsigned int *tmbase)
> +{
> + unsigned long mul;
> +
> + mul = DIV_ROUND_UP(in_freq, out_freq);
> + if (mul > MAX_TMBASE_STEPS * 512)
> + return -EINVAL;
> +
> + if (mul <= MAX_TMBASE_STEPS) {
> + *divider = 1;
> + *tmbase = mul;
> + } else if (mul <= MAX_TMBASE_STEPS * 8) {
> + *divider = 8;
> + *tmbase = mul / 8;
> + *tmbase += mul % 8;
> + } else if (mul <= MAX_TMBASE_STEPS * 64) {
> + *divider = 64;
> + *tmbase = mul / 64;
> + *tmbase += mul % 64;
> + } else if (mul <= MAX_TMBASE_STEPS * 512) {
> + *divider = 512;
> + *tmbase = mul / 512;
> + *tmbase += mul % 512;
> + }
> +
> + return 0;
> +}
> +
> +static void img_pwm_ch_config(struct img_pwm_chip *chip,
> + unsigned int ch_num, unsigned int divider,
> + unsigned int tmbase_steps, unsigned int duty_steps)
> +{
> + unsigned int div;
> + unsigned long val;
> +
> + switch (divider) {
> + case 1:
> + div = NO_SUB_DIV;
> + break;
> + case 8:
> + div = SUB_DIV0;
> + break;
> + case 64:
> + div = SUB_DIV1;
> + break;
> + case 512:
> + div = SUB_DIV0_DIV1;
> + break;
> + }
> +
> + val = img_pwm_readl(chip, CR_PWM_CTRL_CFG);
> + val &= ~PWM_CH_DIV_MASK(ch_num);
> + val |= (div << PWM_CH_DIV_SHIFT(ch_num)) & PWM_CH_DIV_MASK(ch_num);
> + img_pwm_writel(chip, CR_PWM_CTRL_CFG, val);
> +
> + duty_steps = duty_steps << DUTY_SHIFT;
> + tmbase_steps = tmbase_steps << TMBASE_SHIFT;
> + val = (duty_steps | tmbase_steps);
Why not do:
val = (duty_steps << DUTY_SHIFT) | (tmbase_steps << TMBASE_SHIFT):
I don't see any need for the intermediate assignments.
> + img_pwm_writel(chip, CR_PWM_CH_CFG(ch_num), val);
> +}
> +
> +static int img_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> + int duty_ns, int period_ns)
> +{
> + unsigned int divider;
> + unsigned int duty_steps;
> + unsigned int tmbase_steps;
> + unsigned long output_clk_hz;
> + unsigned long input_clk_hz;
> + struct img_pwm_chip *pwm_chip;
> +
> + pwm_chip = to_img_pwm_chip(chip);
> +
> + input_clk_hz = clk_get_rate(pwm_chip->clk);
> + output_clk_hz = DIV_ROUND_UP(NSEC_PER_SEC, period_ns);
> + if (img_pwm_get_div_and_tmbase(chip, input_clk_hz,
> + output_clk_hz, ÷r, &tmbase_steps) < 0) {
> + dev_err(chip->dev,
> + "failed to configure timebase steps/divider value.\n");
> + return -EINVAL;
> + }
> +
> + duty_steps = (tmbase_steps * duty_ns) / (period_ns);
Unnecessary parenthesis.
> + img_pwm_ch_config(pwm_chip, pwm->hwpwm, divider,
> + tmbase_steps, duty_steps);
> +
> + return 0;
> +}
> +
> +static int img_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + unsigned int val = 0;
No need to initialize val (there are other places where this is done as well).
> + struct img_pwm_chip *pwm_chip;
> +
> + pwm_chip = to_img_pwm_chip(chip);
> +
> + val = img_pwm_readl(pwm_chip, CR_PWM_CTRL_CFG);
> + val |= BIT(pwm->hwpwm);
> + img_pwm_writel(pwm_chip, CR_PWM_CTRL_CFG, val);
> + regmap_read(pwm_chip->periph_regs, CR_PERIP_PWM_PDM_CONTROL, &val);
> + val &= ~BIT(PWM_PDM_CH_CTRL_SHIFT(pwm->hwpwm));
> + regmap_write(pwm_chip->periph_regs, CR_PERIP_PWM_PDM_CONTROL, val);
> +
> + return 0;
> +}
> +
> +static void img_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + unsigned int val = 0;
> + struct img_pwm_chip *pwm_chip;
> +
> + pwm_chip = to_img_pwm_chip(chip);
> +
> + val = img_pwm_readl(pwm_chip, CR_PWM_CTRL_CFG);
> + val &= ~BIT(pwm->hwpwm);
> + img_pwm_writel(pwm_chip, CR_PWM_CTRL_CFG, val);
> + regmap_read(pwm_chip->periph_regs, CR_PERIP_PWM_PDM_CONTROL, &val);
> + val |= BIT(PWM_PDM_CH_CTRL_SHIFT(pwm->hwpwm));
> + regmap_write(pwm_chip->periph_regs, CR_PERIP_PWM_PDM_CONTROL, val);
FYI there's regmap_update_bits() which will do the read-modify-write sequence.
> +}
> +
> +static const struct pwm_ops img_pwm_ops = {
> + .config = img_pwm_config,
> + .enable = img_pwm_enable,
> + .disable = img_pwm_disable,
> + .owner = THIS_MODULE,
> +};
> +
> +static int img_pwm_probe(struct platform_device *pdev)
> +{
> + int ret;
> + struct resource *res;
> + struct img_pwm_chip *pwm;
> +
> + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> + if (!pwm)
> + return -ENOMEM;
> +
> + pwm->dev = &pdev->dev;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + pwm->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(pwm->base))
> + return PTR_ERR(pwm->base);
> +
> + pwm->periph_regs = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
> + "img,cr-periph");
> + if (IS_ERR(pwm->periph_regs))
> + return PTR_ERR(pwm->periph_regs);
> +
> + pwm->clk = devm_clk_get(&pdev->dev, "pwm");
> + if (IS_ERR(pwm->clk)) {
> + dev_err(&pdev->dev, "failed to get the clock.\n");
> + return PTR_ERR(pwm->clk);
> + }
> +
> + ret = clk_prepare_enable(pwm->clk);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "could not prepare or enable pwm clock.\n");
> + return ret;
> + }
> +
> + pwm->chip.dev = &pdev->dev;
> + pwm->chip.ops = &img_pwm_ops;
> + pwm->chip.base = -1;
> + pwm->chip.npwm = NUM_PWM;
> +
> + ret = pwmchip_add(&pwm->chip);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
> + clk_disable_unprepare(pwm->clk);
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, pwm);
> +
> + return 0;
> +}
> +
> +static int img_pwm_remove(struct platform_device *pdev)
> +{
> + int i;
> + unsigned int val = 0;
> + struct img_pwm_chip *pwm_chip = platform_get_drvdata(pdev);
> +
> + for (i = 0; i < NUM_PWM; i++) {
> + val = img_pwm_readl(pwm_chip, CR_PWM_CTRL_CFG);
> + val &= ~BIT(i);
> + img_pwm_writel(pwm_chip, CR_PWM_CTRL_CFG, val);
> + }
> +
> + clk_disable_unprepare(pwm_chip->clk);
> +
> + return pwmchip_remove(&pwm_chip->chip);
> +}
> +
> +static const struct of_device_id img_pwm_of_match[] = {
> + { .compatible = "img,pistachio-pwm", },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, img_pwm_of_match);
> +
> +static struct platform_driver img_pwm_driver = {
> + .driver = {
> + .name = "img-pwm",
> + .of_match_table = of_match_ptr(img_pwm_of_match),
> + },
> + .probe = img_pwm_probe,
> + .remove = img_pwm_remove,
> +};
> +module_platform_driver(img_pwm_driver);
> +
> +MODULE_AUTHOR("Sai Masarapu <Sai.Masarapu@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Imagination Technologies PWM DAC driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.7.0.4
>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
