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From d7a403ac584a5ed4a871c66deeb60fd887074ffc Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Wed, 8 May 2013 11:46:50 +0100
Subject: [PATCH] enabling the realtime clock 1-wire chip DS1307 and 1-wire on
GPIO4 (as a module)
1-wire: Add support for configuring pin for w1-gpio kernel module
See: https://github.com/raspberrypi/linux/pull/457
Add bitbanging pullups, use them for w1-gpio
Allows parasite power to work, uses module option pullup=1
bcm2708: Ensure 1-wire pullup is disabled by default, and expose as module parameter
Signed-off-by: Alex J Lennon <ajlennon@dynamicdevices.co.uk>
w1-gpio: Add gpiopin module parameter and correctly free up gpio pull-up pin, if set
Signed-off-by: Alex J Lennon <ajlennon@dynamicdevices.co.uk>
w1-gpio: Sort out the pullup/parasitic power tangle
---
drivers/w1/masters/w1-gpio.c | 69 ++++++++++++++++++++++++++++++++++++++++----
drivers/w1/w1.h | 6 ++++
drivers/w1/w1_int.c | 14 +++++++++
drivers/w1/w1_io.c | 18 ++++++++++--
include/linux/w1-gpio.h | 1 +
5 files changed, 99 insertions(+), 9 deletions(-)
--- a/drivers/w1/masters/w1-gpio.c
+++ b/drivers/w1/masters/w1-gpio.c
@@ -23,6 +23,19 @@
#include "../w1.h"
#include "../w1_int.h"
+static int w1_gpio_pullup = 0;
+static int w1_gpio_pullup_orig = 0;
+module_param_named(pullup, w1_gpio_pullup, int, 0);
+MODULE_PARM_DESC(pullup, "Enable parasitic power (power on data) mode");
+static int w1_gpio_pullup_pin = -1;
+static int w1_gpio_pullup_pin_orig = -1;
+module_param_named(extpullup, w1_gpio_pullup_pin, int, 0);
+MODULE_PARM_DESC(extpullup, "GPIO external pullup pin number");
+static int w1_gpio_pin = -1;
+static int w1_gpio_pin_orig = -1;
+module_param_named(gpiopin, w1_gpio_pin, int, 0);
+MODULE_PARM_DESC(gpiopin, "GPIO pin number");
+
static u8 w1_gpio_set_pullup(void *data, int delay)
{
struct w1_gpio_platform_data *pdata = data;
@@ -67,6 +80,16 @@ static u8 w1_gpio_read_bit(void *data)
return gpio_get_value(pdata->pin) ? 1 : 0;
}
+static void w1_gpio_bitbang_pullup(void *data, u8 on)
+{
+ struct w1_gpio_platform_data *pdata = data;
+
+ if (on)
+ gpio_direction_output(pdata->pin, 1);
+ else
+ gpio_direction_input(pdata->pin);
+}
+
#if defined(CONFIG_OF)
static const struct of_device_id w1_gpio_dt_ids[] = {
{ .compatible = "w1-gpio" },
@@ -80,6 +103,7 @@ static int w1_gpio_probe_dt(struct platf
struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
struct device_node *np = pdev->dev.of_node;
int gpio;
+ u32 value;
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
@@ -88,6 +112,9 @@ static int w1_gpio_probe_dt(struct platf
if (of_get_property(np, "linux,open-drain", NULL))
pdata->is_open_drain = 1;
+ if (of_property_read_u32(np, "rpi,parasitic-power", &value) == 0)
+ pdata->parasitic_power = (value != 0);
+
gpio = of_get_gpio(np, 0);
if (gpio < 0) {
if (gpio != -EPROBE_DEFER)
@@ -103,7 +130,7 @@ static int w1_gpio_probe_dt(struct platf
if (gpio == -EPROBE_DEFER)
return gpio;
/* ignore other errors as the pullup gpio is optional */
- pdata->ext_pullup_enable_pin = gpio;
+ pdata->ext_pullup_enable_pin = (gpio >= 0) ? gpio : -1;
pdev->dev.platform_data = pdata;
@@ -113,13 +140,15 @@ static int w1_gpio_probe_dt(struct platf
static int w1_gpio_probe(struct platform_device *pdev)
{
struct w1_bus_master *master;
- struct w1_gpio_platform_data *pdata;
+ struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
int err;
- if (of_have_populated_dt()) {
- err = w1_gpio_probe_dt(pdev);
- if (err < 0)
- return err;
+ if(pdata == NULL) {
+ if (of_have_populated_dt()) {
+ err = w1_gpio_probe_dt(pdev);
+ if (err < 0)
+ return err;
+ }
}
pdata = dev_get_platdata(&pdev->dev);
@@ -136,6 +165,22 @@ static int w1_gpio_probe(struct platform
return -ENOMEM;
}
+ w1_gpio_pin_orig = pdata->pin;
+ w1_gpio_pullup_pin_orig = pdata->ext_pullup_enable_pin;
+ w1_gpio_pullup_orig = pdata->parasitic_power;
+
+ if(gpio_is_valid(w1_gpio_pin)) {
+ pdata->pin = w1_gpio_pin;
+ pdata->ext_pullup_enable_pin = -1;
+ pdata->parasitic_power = -1;
+ }
+ pdata->parasitic_power |= w1_gpio_pullup;
+ if(gpio_is_valid(w1_gpio_pullup_pin)) {
+ pdata->ext_pullup_enable_pin = w1_gpio_pullup_pin;
+ }
+
+ dev_info(&pdev->dev, "gpio pin %d, external pullup pin %d, parasitic power %d\n", pdata->pin, pdata->ext_pullup_enable_pin, pdata->parasitic_power);
+
err = devm_gpio_request(&pdev->dev, pdata->pin, "w1");
if (err) {
dev_err(&pdev->dev, "gpio_request (pin) failed\n");
@@ -165,6 +210,14 @@ static int w1_gpio_probe(struct platform
master->set_pullup = w1_gpio_set_pullup;
}
+ if (pdata->parasitic_power) {
+ if (pdata->is_open_drain)
+ printk(KERN_ERR "w1-gpio 'pullup'(parasitic power) "
+ "option doesn't work with open drain GPIO\n");
+ else
+ master->bitbang_pullup = w1_gpio_bitbang_pullup;
+ }
+
err = w1_add_master_device(master);
if (err) {
dev_err(&pdev->dev, "w1_add_master device failed\n");
@@ -195,6 +248,10 @@ static int w1_gpio_remove(struct platfor
w1_remove_master_device(master);
+ pdata->pin = w1_gpio_pin_orig;
+ pdata->ext_pullup_enable_pin = w1_gpio_pullup_pin_orig;
+ pdata->parasitic_power = w1_gpio_pullup_orig;
+
return 0;
}
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -171,6 +171,12 @@ struct w1_bus_master
u8 (*set_pullup)(void *, int);
+ /**
+ * Turns the pullup on/off in bitbanging mode, takes an on/off argument.
+ * @return -1=Error, 0=completed
+ */
+ void (*bitbang_pullup) (void *, u8);
+
void (*search)(void *, struct w1_master *,
u8, w1_slave_found_callback);
};
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -122,6 +122,20 @@ int w1_add_master_device(struct w1_bus_m
return(-EINVAL);
}
+ /* bitbanging hardware uses bitbang_pullup, other hardware uses set_pullup
+ * and takes care of timing itself */
+ if (!master->write_byte && !master->touch_bit && master->set_pullup) {
+ printk(KERN_ERR "w1_add_master_device: set_pullup requires "
+ "write_byte or touch_bit, disabling\n");
+ master->set_pullup = NULL;
+ }
+
+ if (master->set_pullup && master->bitbang_pullup) {
+ printk(KERN_ERR "w1_add_master_device: set_pullup should not "
+ "be set when bitbang_pullup is used, disabling\n");
+ master->set_pullup = NULL;
+ }
+
/* Lock until the device is added (or not) to w1_masters. */
mutex_lock(&w1_mlock);
/* Search for the first available id (starting at 1). */
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -134,10 +134,22 @@ static void w1_pre_write(struct w1_maste
static void w1_post_write(struct w1_master *dev)
{
if (dev->pullup_duration) {
- if (dev->enable_pullup && dev->bus_master->set_pullup)
- dev->bus_master->set_pullup(dev->bus_master->data, 0);
- else
+ if (dev->enable_pullup) {
+ if (dev->bus_master->set_pullup) {
+ dev->bus_master->set_pullup(dev->
+ bus_master->data,
+ 0);
+ } else if (dev->bus_master->bitbang_pullup) {
+ dev->bus_master->
+ bitbang_pullup(dev->bus_master->data, 1);
msleep(dev->pullup_duration);
+ dev->bus_master->
+ bitbang_pullup(dev->bus_master->data, 0);
+ }
+ } else {
+ msleep(dev->pullup_duration);
+ }
+
dev->pullup_duration = 0;
}
}
--- a/include/linux/w1-gpio.h
+++ b/include/linux/w1-gpio.h
@@ -18,6 +18,7 @@
struct w1_gpio_platform_data {
unsigned int pin;
unsigned int is_open_drain:1;
+ unsigned int parasitic_power:1;
void (*enable_external_pullup)(int enable);
unsigned int ext_pullup_enable_pin;
unsigned int pullup_duration;
|
