* [PATCH v10 1/2] pwm: add support for atmel-hlcdc-pwm device
2014-10-07 13:38 [PATCH v10 0/2] pwm: add support for atmel-hlcdc-pwm device Boris Brezillon
@ 2014-10-07 13:38 ` Boris Brezillon
2014-10-07 13:38 ` [PATCH v10 2/2] pwm: add DT bindings documentation for atmel-hlcdc-pwm driver Boris Brezillon
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Boris Brezillon @ 2014-10-07 13:38 UTC (permalink / raw)
To: linux-arm-kernel
The HLCDC IP available in some Atmel SoCs (i.e. at91sam9x5, at91sam9n12
or sama5d3 families for instance) provides a PWM device.
This driver add support for a PWM chip exposing a single PWM device (which
will most likely be used to drive a backlight device).
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Anthony Harivel <anthony.harivel@emtrion.de>
Tested-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
---
drivers/pwm/Kconfig | 11 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-atmel-hlcdc.c | 259 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 271 insertions(+)
create mode 100644 drivers/pwm/pwm-atmel-hlcdc.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index b800783..6018af6 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -50,6 +50,17 @@ config PWM_ATMEL
To compile this driver as a module, choose M here: the module
will be called pwm-atmel.
+config PWM_ATMEL_HLCDC_PWM
+ tristate "Atmel HLCDC PWM support"
+ depends on MFD_ATMEL_HLCDC
+ help
+ Generic PWM framework driver for the PWM output of the HLCDC
+ (Atmel High-end LCD Controller). This PWM output is mainly used
+ to control the LCD backlight.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-atmel-hlcdc.
+
config PWM_ATMEL_TCB
tristate "Atmel TC Block PWM support"
depends on ATMEL_TCLIB && OF
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index f8c577d..eb0aae5 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_PWM) += core.o
obj-$(CONFIG_PWM_SYSFS) += sysfs.o
obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
+obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
diff --git a/drivers/pwm/pwm-atmel-hlcdc.c b/drivers/pwm/pwm-atmel-hlcdc.c
new file mode 100644
index 0000000..eaf8b12
--- /dev/null
+++ b/drivers/pwm/pwm-atmel-hlcdc.c
@@ -0,0 +1,259 @@
+/*
+ * Copyright (C) 2014 Free Electrons
+ * Copyright (C) 2014 Atmel
+ *
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * 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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/mfd/atmel-hlcdc.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+
+#define ATMEL_HLCDC_PWMCVAL_MASK GENMASK(15, 8)
+#define ATMEL_HLCDC_PWMCVAL(x) (((x) << 8) & ATMEL_HLCDC_PWMCVAL_MASK)
+#define ATMEL_HLCDC_PWMPOL BIT(4)
+#define ATMEL_HLCDC_PWMPS_MASK GENMASK(2, 0)
+#define ATMEL_HLCDC_PWMPS_MAX 0x6
+#define ATMEL_HLCDC_PWMPS(x) ((x) & ATMEL_HLCDC_PWMPS_MASK)
+
+struct atmel_hlcdc_pwm {
+ struct pwm_chip chip;
+ struct atmel_hlcdc *hlcdc;
+ struct clk *cur_clk;
+};
+
+static inline struct atmel_hlcdc_pwm *to_atmel_hlcdc_pwm(struct pwm_chip *chip)
+{
+ return container_of(chip, struct atmel_hlcdc_pwm, chip);
+}
+
+static int atmel_hlcdc_pwm_config(struct pwm_chip *c,
+ struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
+ struct atmel_hlcdc *hlcdc = chip->hlcdc;
+ struct clk *new_clk = hlcdc->slow_clk;
+ u64 pwmcval = duty_ns * 256;
+ unsigned long clk_freq;
+ u64 clk_period_ns;
+ u32 pwmcfg;
+ int pres;
+
+ clk_freq = clk_get_rate(new_clk);
+ clk_period_ns = (u64)NSEC_PER_SEC * 256;
+ do_div(clk_period_ns, clk_freq);
+
+ if (clk_period_ns > period_ns) {
+ new_clk = hlcdc->sys_clk;
+ clk_freq = clk_get_rate(new_clk);
+ clk_period_ns = (u64)NSEC_PER_SEC * 256;
+ do_div(clk_period_ns, clk_freq);
+ }
+
+ for (pres = 0; pres <= ATMEL_HLCDC_PWMPS_MAX; pres++)
+ if ((clk_period_ns << pres) >= period_ns)
+ break;
+
+ if (pres > ATMEL_HLCDC_PWMPS_MAX)
+ return -EINVAL;
+
+ pwmcfg = ATMEL_HLCDC_PWMPS(pres);
+
+ if (new_clk != chip->cur_clk) {
+ u32 gencfg = 0;
+ int ret;
+
+ ret = clk_prepare_enable(new_clk);
+ if (ret)
+ return ret;
+
+ clk_disable_unprepare(chip->cur_clk);
+ chip->cur_clk = new_clk;
+
+ if (new_clk == hlcdc->sys_clk)
+ gencfg = ATMEL_HLCDC_CLKPWMSEL;
+
+ ret = regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(0),
+ ATMEL_HLCDC_CLKPWMSEL, gencfg);
+ if (ret)
+ return ret;
+ }
+
+ do_div(pwmcval, period_ns);
+
+ /*
+ * The PWM duty cycle is configurable from 0/256 to 255/256 of the
+ * period cycle. Hence we can't set a duty cycle occupying the
+ * whole period cycle if we're asked to.
+ * Set it to 255 if pwmcval is greater than 256.
+ */
+ if (pwmcval > 255)
+ pwmcval = 255;
+
+ pwmcfg |= ATMEL_HLCDC_PWMCVAL(pwmcval);
+
+ return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
+ ATMEL_HLCDC_PWMCVAL_MASK |
+ ATMEL_HLCDC_PWMPS_MASK,
+ pwmcfg);
+}
+
+static int atmel_hlcdc_pwm_set_polarity(struct pwm_chip *c,
+ struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
+ struct atmel_hlcdc *hlcdc = chip->hlcdc;
+ u32 cfg = 0;
+
+ if (polarity == PWM_POLARITY_NORMAL)
+ cfg = ATMEL_HLCDC_PWMPOL;
+
+ return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
+ ATMEL_HLCDC_PWMPOL, cfg);
+}
+
+static int atmel_hlcdc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
+{
+ struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
+ struct atmel_hlcdc *hlcdc = chip->hlcdc;
+ u32 status;
+ int ret;
+
+ ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_EN, ATMEL_HLCDC_PWM);
+ if (ret)
+ return ret;
+
+ while (true) {
+ ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
+ if (ret)
+ return ret;
+
+ if ((status & ATMEL_HLCDC_PWM) != 0)
+ break;
+
+ usleep_range(1, 10);
+ }
+
+ return 0;
+}
+
+static void atmel_hlcdc_pwm_disable(struct pwm_chip *c,
+ struct pwm_device *pwm)
+{
+ struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
+ struct atmel_hlcdc *hlcdc = chip->hlcdc;
+ u32 status;
+ int ret;
+
+ ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_DIS, ATMEL_HLCDC_PWM);
+ if (ret)
+ return;
+
+ while (true) {
+ ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
+ if (ret)
+ return;
+
+ if ((status & ATMEL_HLCDC_PWM) == 0)
+ break;
+
+ usleep_range(1, 10);
+ }
+}
+
+static const struct pwm_ops atmel_hlcdc_pwm_ops = {
+ .config = atmel_hlcdc_pwm_config,
+ .set_polarity = atmel_hlcdc_pwm_set_polarity,
+ .enable = atmel_hlcdc_pwm_enable,
+ .disable = atmel_hlcdc_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int atmel_hlcdc_pwm_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct atmel_hlcdc_pwm *chip;
+ struct atmel_hlcdc *hlcdc;
+ int ret;
+
+ hlcdc = dev_get_drvdata(dev->parent);
+
+ chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+ if (!chip)
+ return -ENOMEM;
+
+ ret = clk_prepare_enable(hlcdc->periph_clk);
+ if (ret)
+ return ret;
+
+ chip->hlcdc = hlcdc;
+ chip->chip.ops = &atmel_hlcdc_pwm_ops;
+ chip->chip.dev = dev;
+ chip->chip.base = -1;
+ chip->chip.npwm = 1;
+ chip->chip.of_xlate = of_pwm_xlate_with_flags;
+ chip->chip.of_pwm_n_cells = 3;
+ chip->chip.can_sleep = 1;
+
+ ret = pwmchip_add(&chip->chip);
+ if (ret) {
+ clk_disable_unprepare(hlcdc->periph_clk);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, chip);
+
+ return 0;
+}
+
+static int atmel_hlcdc_pwm_remove(struct platform_device *pdev)
+{
+ struct atmel_hlcdc_pwm *chip = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = pwmchip_remove(&chip->chip);
+ if (ret)
+ return ret;
+
+ clk_disable_unprepare(chip->hlcdc->periph_clk);
+
+ return 0;
+}
+
+static const struct of_device_id atmel_hlcdc_pwm_dt_ids[] = {
+ { .compatible = "atmel,hlcdc-pwm" },
+ { /* sentinel */ },
+};
+
+static struct platform_driver atmel_hlcdc_pwm_driver = {
+ .driver = {
+ .name = "atmel-hlcdc-pwm",
+ .of_match_table = atmel_hlcdc_pwm_dt_ids,
+ },
+ .probe = atmel_hlcdc_pwm_probe,
+ .remove = atmel_hlcdc_pwm_remove,
+};
+module_platform_driver(atmel_hlcdc_pwm_driver);
+
+MODULE_ALIAS("platform:atmel-hlcdc-pwm");
+MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
+MODULE_DESCRIPTION("Atmel HLCDC PWM driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1
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