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Date: Tue, 16 Jul 2013 02:38:48 +0000
From: "Kim, Milo" <Milo.Kim@...com>
To: "thierry.reding@...il.com" <thierry.reding@...il.com>
CC: "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
"lee.jones@...aro.org" <lee.jones@...aro.org>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
"linus.walleij@...aro.org" <linus.walleij@...aro.org>
Subject: [PATCH 3/3] pwm: add LP3943 PWM driver
This is a part of the LP3943 MFD driver.
LP3943 can be used as a PWM generator, up to 2 channels.
* Two PWM generators
LP3943 has 16 output channels.
Two channels are configurable as PWM generators.
* Supported PWM operations
config, set_polarity, enable and disable
* Manual polarity configuration
No register exists for setting polarity. However, the value of duty can be
calculated as following.
PWM-inversed mode : duty = period - duty
PWM-normal mode : input duty itself
* Pin MUX configuration at each PWM operation - enable and disable
* Register access through exported LP3943 MFD functions
Signed-off-by: Milo Kim <milo.kim@...com>
---
drivers/pwm/Kconfig | 10 +++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-lp3943.c | 192 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 203 insertions(+)
create mode 100644 drivers/pwm/pwm-lp3943.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 75840b5..28a7668 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -81,6 +81,16 @@ config PWM_JZ4740
To compile this driver as a module, choose M here: the module
will be called pwm-jz4740.
+config PWM_LP3943
+ tristate "LP3943 PWM support"
+ depends on MFD_LP3943
+ help
+ Generic PWM framework driver for LP3943. It supports two PWM
+ controllers.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-lp3943.
+
config PWM_LPC32XX
tristate "LPC32XX PWM support"
depends on ARCH_LPC32XX
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 77a8c18..db8e349 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
obj-$(CONFIG_PWM_IMX) += pwm-imx.o
obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o
+obj-$(CONFIG_PWM_LP3943) += pwm-lp3943.o
obj-$(CONFIG_PWM_LPC32XX) += pwm-lpc32xx.o
obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o
diff --git a/drivers/pwm/pwm-lp3943.c b/drivers/pwm/pwm-lp3943.c
new file mode 100644
index 0000000..33e63fa7
--- /dev/null
+++ b/drivers/pwm/pwm-lp3943.c
@@ -0,0 +1,192 @@
+/*
+ * TI/National Semiconductor LP3943 PWM driver
+ *
+ * Copyright (C) 2013 Texas Instruments
+ *
+ * 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; version 2.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mfd/lp3943.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define LP3943_MAX_DUTY 255
+#define LP3943_MIN_PERIOD 6250
+#define LP3943_MAX_PERIOD 1600000
+#define LP3943_NUM_PWMS 2
+
+#define to_lp3943_pwm(_chip) container_of(_chip, struct lp3943_pwm, chip)
+
+struct lp3943_pwm {
+ struct pwm_chip chip;
+ struct lp3943 *l;
+ enum lp3943_pwm_output output[LP3943_NUM_PWMS];
+ bool inversed[LP3943_NUM_PWMS];
+};
+
+static int lp3943_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct lp3943_pwm *lp = to_lp3943_pwm(chip);
+ u8 reg_prescale;
+ u8 reg_duty;
+ u8 val;
+ int err;
+
+ /*
+ * How to configure the LP3943 PWMs
+ *
+ * 1) Period = 6250 ~ 1600000
+ * 2) Prescale = period / 6250 -1
+ * 3) Duty = 'input duty'(normal) or 'period - duty'(inversed)
+ *
+ * Prescale and duty are register values
+ */
+
+ if (pwm->hwpwm == 0) {
+ reg_prescale = LP3943_REG_PRESCALE0;
+ reg_duty = LP3943_REG_PWM0;
+ } else if (pwm->hwpwm == 1) {
+ reg_prescale = LP3943_REG_PRESCALE1;
+ reg_duty = LP3943_REG_PWM1;
+ } else {
+ return -EINVAL;
+ }
+
+ period_ns = clamp(period_ns, LP3943_MIN_PERIOD, LP3943_MAX_PERIOD);
+ val = (u8)(period_ns / LP3943_MIN_PERIOD - 1);
+
+ err = lp3943_write_byte(lp->l, reg_prescale, val);
+ if (err)
+ return err;
+
+ if (lp->inversed[pwm->hwpwm])
+ val = (u8)((period_ns - duty_ns) * LP3943_MAX_DUTY / period_ns);
+ else
+ val = (u8)(duty_ns * LP3943_MAX_DUTY / period_ns);
+
+ return lp3943_write_byte(lp->l, reg_duty, val);
+}
+
+static int lp3943_pwm_set_polarity(struct pwm_chip *chip,
+ struct pwm_device *pwm, enum pwm_polarity polarity)
+{
+ struct lp3943_pwm *lp = to_lp3943_pwm(chip);
+
+ if (polarity == PWM_POLARITY_INVERSED)
+ lp->inversed[pwm->hwpwm] = true;
+ else
+ lp->inversed[pwm->hwpwm] = false;
+
+ return 0;
+}
+
+static int lp3943_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct lp3943_pwm *lp = to_lp3943_pwm(chip);
+ const struct lp3943_reg_cfg *mux = lp->l->mux_cfg;
+ int offset = lp->output[pwm->hwpwm] - 1;
+ u8 val;
+
+ if (pwm->hwpwm == 0)
+ val = LP3943_DIM_PWM0;
+ else if (pwm->hwpwm == 1)
+ val = LP3943_DIM_PWM1;
+ else
+ return -EINVAL;
+
+ return lp3943_update_bits(lp->l, mux[offset].reg, mux[offset].mask,
+ val << mux[offset].shift);
+}
+
+static void lp3943_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct lp3943_pwm *lp = to_lp3943_pwm(chip);
+ const struct lp3943_reg_cfg *mux = lp->l->mux_cfg;
+ int offset = lp->output[pwm->hwpwm] - 1;
+ u8 val;
+
+ /*
+ * LP3943 outputs are open-drain, so the pin should be configured
+ * when the PWM is disabled.
+ *
+ * - inversed: output low
+ * - normal: output Hi-Z
+ */
+
+ if (lp->inversed[pwm->hwpwm])
+ val = LP3943_GPIO_OUT_LOW << mux[offset].shift;
+ else
+ val = LP3943_GPIO_OUT_HIGH << mux[offset].shift;
+
+ lp3943_update_bits(lp->l, mux[offset].reg, mux[offset].mask, val);
+}
+
+static const struct pwm_ops lp3943_pwm_ops = {
+ .config = lp3943_pwm_config,
+ .set_polarity = lp3943_pwm_set_polarity,
+ .enable = lp3943_pwm_enable,
+ .disable = lp3943_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int lp3943_pwm_probe(struct platform_device *pdev)
+{
+ struct lp3943 *l = dev_get_drvdata(pdev->dev.parent);
+ struct lp3943_platform_data *pdata = l->pdata;
+ struct lp3943_pwm *lp;
+ int num_pwms = 0;
+ int ret;
+
+ lp = devm_kzalloc(&pdev->dev, sizeof(struct lp3943_pwm), GFP_KERNEL);
+ if (!lp)
+ return -ENOMEM;
+
+ if (pdata->pwm0 != LP3943_PWM_INVALID)
+ lp->output[num_pwms++] = pdata->pwm0;
+
+ if (pdata->pwm1 != LP3943_PWM_INVALID)
+ lp->output[num_pwms++] = pdata->pwm1;
+
+ lp->l = l;
+ lp->chip.dev = &pdev->dev;
+ lp->chip.ops = &lp3943_pwm_ops;
+ lp->chip.npwm = num_pwms;
+
+ platform_set_drvdata(pdev, lp);
+
+ ret = pwmchip_add(&lp->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to add PWM chip, err:%d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int lp3943_pwm_remove(struct platform_device *pdev)
+{
+ struct lp3943_pwm *lp = platform_get_drvdata(pdev);
+ return pwmchip_remove(&lp->chip);
+}
+
+static struct platform_driver lp3943_pwm_driver = {
+ .probe = lp3943_pwm_probe,
+ .remove = lp3943_pwm_remove,
+ .driver = {
+ .name = "lp3943-pwm",
+ .owner = THIS_MODULE,
+ },
+};
+module_platform_driver(lp3943_pwm_driver);
+
+MODULE_DESCRIPTION("LP3943 PWM driver");
+MODULE_AUTHOR("Milo Kim");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:lp3943-pwm");
--
1.7.9.5
Best Regards,
Milo
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