[RFC PATCH 2/3] pwm: Add PWM driver for OMAP using dual-mode timers
Neil Armstrong
narmstrong at baylibre.com
Fri Oct 16 05:27:32 PDT 2015
Adds support for using a OMAP dual-mode timer with PWM capability
as a Linux PWM device. The driver controls the timer by using the
dmtimer API.
Add a platform_data structure for each pwm-omap-dmtimer nodes containing
the dmtimers functions in order to get driver not rely on platform
specific functions.
Cc: Grant Erickson <marathon96 at gmail.com>
Cc: NeilBrown <neilb at suse.de>
Cc: Joachim Eastwood <manabian at gmail.com>
Suggested-by: Tony Lindgren <tony at atomide.com>
Signed-off-by: Neil Armstrong <narmstrong at baylibre.com>
---
.../devicetree/bindings/pwm/pwm-omap-dmtimer.txt | 18 ++
drivers/pwm/Kconfig | 9 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-omap-dmtimer.c | 322 +++++++++++++++++++++
include/linux/platform_data/pwm_omap_dmtimer.h | 69 +++++
5 files changed, 419 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt
create mode 100644 drivers/pwm/pwm-omap-dmtimer.c
create mode 100644 include/linux/platform_data/pwm_omap_dmtimer.h
diff --git a/Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt b/Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt
new file mode 100644
index 0000000..7f27606
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt
@@ -0,0 +1,18 @@
+* OMAP PWM for dual-mode timers
+
+Required properties:
+- compatible: Shall contain "ti,omap-dmtimer-pwm".
+- ti,timers: phandle to PWM capable OMAP timer. See arm/omap/timer.txt for info
+ about these timers.
+- #pwm-cells: Should be 3. See pwm.txt in this directory for a description of
+ the cells format.
+
+Optiomal properties:
+- ti,prescaler: Should be a value between 0 and 7, see the timers datasheet
+
+Example:
+ pwm: omap-pwm {
+ compatible = "ti,omap-pwm";
+ ti,timers = <&timer9>;
+ #pwm-cells = <3>;
+ };
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 062630a..2da60f8 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -240,6 +240,15 @@ config PWM_MXS
To compile this driver as a module, choose M here: the module
will be called pwm-mxs.
+config PWM_OMAP_DMTIMER
+ tristate "OMAP Dual-Mode Timer PWM support"
+ depends on OF && ARCH_OMAP && OMAP_DM_TIMER
+ help
+ Generic PWM framework driver for OMAP Dual-Mode Timer PWM output
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-omap-dmtimer
+
config PWM_PCA9685
tristate "NXP PCA9685 PWM driver"
depends on OF && I2C
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index a0e00c0..af14774 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_PWM_LPSS) += pwm-lpss.o
obj-$(CONFIG_PWM_LPSS_PCI) += pwm-lpss-pci.o
obj-$(CONFIG_PWM_LPSS_PLATFORM) += pwm-lpss-platform.o
obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
+obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o
obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o
obj-$(CONFIG_PWM_PUV3) += pwm-puv3.o
obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
new file mode 100644
index 0000000..c1a4967
--- /dev/null
+++ b/drivers/pwm/pwm-omap-dmtimer.c
@@ -0,0 +1,322 @@
+/*
+ * Copyright (c) 2015 Neil Armstrong <narmstrong at baylibre.com>
+ * Copyright (c) 2014 Joachim Eastwood <manabian at gmail.com>
+ * Copyright (c) 2012 NeilBrown <neilb at suse.de>
+ * Heavily based on earlier code which is:
+ * Copyright (c) 2010 Grant Erickson <marathon96 at gmail.com>
+ *
+ * Also based on pwm-samsung.c
+ *
+ * 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.
+ *
+ * Description:
+ * This file is the core OMAP support for the generic, Linux
+ * PWM driver / controller, using the OMAP's dual-mode timers.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/platform_data/pwm_omap_dmtimer.h>
+
+#define DM_TIMER_LOAD_MIN 0xFFFFFFFE
+
+struct pwm_omap_dmtimer_chip {
+ struct pwm_chip chip;
+ struct mutex mutex;
+ pwm_omap_dmtimer *dm_timer;
+ struct pwm_omap_dmtimer_pdata *pdata;
+ struct platform_device *dm_timer_pdev;
+};
+
+#define to_pwm_omap_dmtimer_chip(chip) container_of(chip,\
+ struct pwm_omap_dmtimer_chip, chip)
+
+static int pwm_omap_dmtimer_calc_value(unsigned long clk_rate, int ns)
+{
+ u64 c;
+
+ c = (u64)clk_rate * ns;
+ do_div(c, NSEC_PER_SEC);
+
+ return DM_TIMER_LOAD_MIN - c;
+}
+
+static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap)
+{
+ /*
+ * According to OMAP 4 TRM section 22.2.4.10 the counter should be
+ * started at 0xFFFFFFFE when overflow and match is used to ensure
+ * that the PWM line is toggled on the first event.
+ *
+ * Note that omap_dm_timer_enable/disable is for register access and
+ * not the timer counter itself.
+ */
+ omap->pdata->enable(omap->dm_timer);
+ omap->pdata->write_counter(omap->dm_timer, DM_TIMER_LOAD_MIN);
+ omap->pdata->disable(omap->dm_timer);
+
+ omap->pdata->start(omap->dm_timer);
+}
+
+static int pwm_omap_dmtimer_enable(struct pwm_chip *chip,
+ struct pwm_device *pwm)
+{
+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
+
+ mutex_lock(&omap->mutex);
+ pwm_omap_dmtimer_start(omap);
+ mutex_unlock(&omap->mutex);
+
+ return 0;
+}
+
+static void pwm_omap_dmtimer_disable(struct pwm_chip *chip,
+ struct pwm_device *pwm)
+{
+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
+
+ mutex_lock(&omap->mutex);
+ omap->pdata->stop(omap->dm_timer);
+ mutex_unlock(&omap->mutex);
+}
+
+static int pwm_omap_dmtimer_config(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
+ int load_value, match_value;
+ struct clk *fclk;
+ unsigned long clk_rate;
+ bool timer_active;
+
+ dev_dbg(chip->dev, "duty cycle: %d, period %d\n", duty_ns, period_ns);
+
+ mutex_lock(&omap->mutex);
+ if (duty_ns == pwm_get_duty_cycle(pwm) &&
+ period_ns == pwm_get_period(pwm)) {
+ /* No change - don't cause any transients. */
+ mutex_unlock(&omap->mutex);
+ return 0;
+ }
+
+ fclk = omap->pdata->get_fclk(omap->dm_timer);
+ if (!fclk) {
+ dev_err(chip->dev, "invalid pmtimer fclk\n");
+ mutex_unlock(&omap->mutex);
+ return -EINVAL;
+ }
+
+ clk_rate = clk_get_rate(fclk);
+ if (!clk_rate) {
+ dev_err(chip->dev, "invalid pmtimer fclk rate\n");
+ mutex_unlock(&omap->mutex);
+ return -EINVAL;
+ }
+
+ dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate);
+
+ /*
+ * Calculate the appropriate load and match values based on the
+ * specified period and duty cycle. The load value determines the
+ * cycle time and the match value determines the duty cycle.
+ */
+ load_value = pwm_omap_dmtimer_calc_value(clk_rate, period_ns);
+ match_value = pwm_omap_dmtimer_calc_value(clk_rate,
+ period_ns - duty_ns);
+
+ /*
+ * We MUST stop the associated dual-mode timer before attempting to
+ * write its registers, but calls to omap_dm_timer_start/stop must
+ * be balanced so check if timer is active before calling timer_stop.
+ */
+ timer_active = pm_runtime_active(&omap->dm_timer_pdev->dev);
+ if (timer_active)
+ omap->pdata->stop(omap->dm_timer);
+
+ omap->pdata->set_load(omap->dm_timer, true, load_value);
+ omap->pdata->set_match(omap->dm_timer, true, match_value);
+
+ dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n",
+ load_value, load_value, match_value, match_value);
+
+ omap->pdata->set_pwm(omap->dm_timer,
+ pwm->polarity == PWM_POLARITY_INVERSED,
+ true,
+ PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
+
+ /* If config was called while timer was running it must be reenabled. */
+ if (timer_active)
+ pwm_omap_dmtimer_start(omap);
+
+ mutex_unlock(&omap->mutex);
+
+ return 0;
+}
+
+static int pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
+
+ /*
+ * PWM core will not call set_polarity while PWM is enabled so it's
+ * safe to reconfigure the timer here without stopping it first.
+ */
+ mutex_lock(&omap->mutex);
+ omap->pdata->set_pwm(omap->dm_timer,
+ polarity == PWM_POLARITY_INVERSED,
+ true,
+ PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
+ mutex_unlock(&omap->mutex);
+
+ return 0;
+}
+
+static const struct pwm_ops pwm_omap_dmtimer_ops = {
+ .enable = pwm_omap_dmtimer_enable,
+ .disable = pwm_omap_dmtimer_disable,
+ .config = pwm_omap_dmtimer_config,
+ .set_polarity = pwm_omap_dmtimer_set_polarity,
+ .owner = THIS_MODULE,
+};
+
+static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *timer;
+ struct pwm_omap_dmtimer_chip *omap;
+ struct pwm_omap_dmtimer_pdata *pdata;
+ pwm_omap_dmtimer *dm_timer;
+ u32 prescaler;
+ int status;
+
+ if (!dev_get_platdata(&pdev->dev)) {
+ dev_err(&pdev->dev, "Missing dmtimer platform data\n");
+ return -EINVAL;
+ }
+
+ pdata = dev_get_platdata(&pdev->dev);
+ if (!pdata->request_by_node ||
+ !pdata->free ||
+ !pdata->enable ||
+ !pdata->disable ||
+ !pdata->get_fclk ||
+ !pdata->start ||
+ !pdata->stop ||
+ !pdata->set_load ||
+ !pdata->set_match ||
+ !pdata->set_pwm ||
+ !pdata->set_prescaler ||
+ !pdata->write_counter) {
+ dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n");
+ return -EINVAL;
+ }
+
+ timer = of_parse_phandle(np, "ti,timers", 0);
+ if (!timer)
+ return -ENODEV;
+
+ if (!of_get_property(timer, "ti,timer-pwm", NULL)) {
+ dev_err(&pdev->dev, "Missing ti,timer-pwm capability\n");
+ return -ENODEV;
+ }
+
+ dm_timer = pdata->request_by_node(timer);
+ if (!dm_timer)
+ return -EPROBE_DEFER;
+
+ omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL);
+ if (!omap)
+ return -ENOMEM;
+
+ omap->pdata = pdata;
+ omap->dm_timer = dm_timer;
+ omap->dm_timer_pdev = of_find_device_by_node(timer);
+ if (!omap->dm_timer_pdev) {
+ dev_err(&pdev->dev, "Unable to find timer pdev\n");
+ return -EINVAL;
+ }
+
+ /*
+ * Ensure that the timer is stopped before we allow PWM core to call
+ * pwm_enable.
+ */
+ if (pm_runtime_active(&omap->dm_timer_pdev->dev))
+ omap->pdata->stop(omap->dm_timer);
+
+ /* setup dmtimer prescaler */
+ if (!of_property_read_u32(pdev->dev.of_node, "ti,prescaler",
+ &prescaler))
+ omap->pdata->set_prescaler(omap->dm_timer, prescaler);
+
+ omap->chip.dev = &pdev->dev;
+ omap->chip.ops = &pwm_omap_dmtimer_ops;
+ omap->chip.base = -1;
+ omap->chip.npwm = 1;
+ omap->chip.of_xlate = of_pwm_xlate_with_flags;
+ omap->chip.of_pwm_n_cells = 3;
+
+ mutex_init(&omap->mutex);
+
+ status = pwmchip_add(&omap->chip);
+ if (status < 0) {
+ dev_err(&pdev->dev, "failed to register PWM\n");
+ omap->pdata->free(omap->dm_timer);
+ return status;
+ }
+
+ platform_set_drvdata(pdev, omap);
+
+ return 0;
+}
+
+static int pwm_omap_dmtimer_remove(struct platform_device *pdev)
+{
+ struct pwm_omap_dmtimer_chip *omap = platform_get_drvdata(pdev);
+
+ if (pm_runtime_active(&omap->dm_timer_pdev->dev))
+ omap->pdata->stop(omap->dm_timer);
+
+ omap->pdata->free(omap->dm_timer);
+
+ mutex_destroy(&omap->mutex);
+
+ return pwmchip_remove(&omap->chip);
+}
+
+static const struct of_device_id pwm_omap_dmtimer_of_match[] = {
+ {.compatible = "ti,omap-dmtimer-pwm"},
+ {}
+};
+MODULE_DEVICE_TABLE(of, pwm_omap_dmtimer_of_match);
+
+static struct platform_driver pwm_omap_dmtimer_driver = {
+ .driver = {
+ .name = "omap-dmtimer-pwm",
+ .of_match_table = of_match_ptr(pwm_omap_dmtimer_of_match),
+ },
+ .probe = pwm_omap_dmtimer_probe,
+ .remove = pwm_omap_dmtimer_remove,
+};
+module_platform_driver(pwm_omap_dmtimer_driver);
+
+MODULE_AUTHOR("Grant Erickson <marathon96 at gmail.com>");
+MODULE_AUTHOR("NeilBrown <neilb at suse.de>");
+MODULE_AUTHOR("Neil Armstrong <narmstrong at baylibre.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers");
diff --git a/include/linux/platform_data/pwm_omap_dmtimer.h b/include/linux/platform_data/pwm_omap_dmtimer.h
new file mode 100644
index 0000000..5938421
--- /dev/null
+++ b/include/linux/platform_data/pwm_omap_dmtimer.h
@@ -0,0 +1,69 @@
+/*
+ * include/linux/platform_data/pwm_omap_dmtimer.h
+ *
+ * OMAP Dual-Mode Timer PWM platform data
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
+ * Tarun Kanti DebBarma <tarun.kanti at ti.com>
+ * Thara Gopinath <thara at ti.com>
+ *
+ * Platform device conversion and hwmod support.
+ *
+ * Copyright (C) 2005 Nokia Corporation
+ * Author: Lauri Leukkunen <lauri.leukkunen at nokia.com>
+ * PWM and clock framework support by Timo Teras.
+ *
+ * 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 SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef __PWM_OMAP_DMTIMER_PDATA_H
+#define __PWM_OMAP_DMTIMER_PDATA_H
+
+/* trigger types */
+#define PWM_OMAP_DMTIMER_TRIGGER_NONE 0x00
+#define PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW 0x01
+#define PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE 0x02
+
+struct omap_dm_timer;
+typedef struct omap_dm_timer pwm_omap_dmtimer;
+
+struct pwm_omap_dmtimer_pdata {
+ pwm_omap_dmtimer *(*request_by_node)(struct device_node *np);
+ int (*free)(pwm_omap_dmtimer *timer);
+
+ void (*enable)(pwm_omap_dmtimer *timer);
+ void (*disable)(pwm_omap_dmtimer *timer);
+
+ struct clk *(*get_fclk)(pwm_omap_dmtimer *timer);
+
+ int (*start)(pwm_omap_dmtimer *timer);
+ int (*stop)(pwm_omap_dmtimer *timer);
+
+ int (*set_load)(pwm_omap_dmtimer *timer, int autoreload,
+ unsigned int value);
+ int (*set_match)(pwm_omap_dmtimer *timer, int enable,
+ unsigned int match);
+ int (*set_pwm)(pwm_omap_dmtimer *timer, int def_on,
+ int toggle, int trigger);
+ int (*set_prescaler)(pwm_omap_dmtimer *timer, int prescaler);
+
+ int (*write_counter)(pwm_omap_dmtimer *timer, unsigned int value);
+};
+
+#endif /* __PWM_OMAP_DMTIMER_PDATA_H */
--
1.9.1
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