From 8ceb69e8548f27305e37866ec3b81a79e1402b1a Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Wed, 4 Feb 2015 12:59:36 +0000
Subject: [PATCH 103/114] w1-gpio: Sort out the pullup/parasitic power tangle
---
arch/arm/boot/dts/w1-gpio-overlay.dts | 4 +++-
arch/arm/boot/dts/w1-gpio-pullup-overlay.dts | 6 +++--
drivers/w1/masters/w1-gpio.c | 36 ++++++++++++++++++----------
include/linux/w1-gpio.h | 1 +
4 files changed, 32 insertions(+), 15 deletions(-)
--- a/arch/arm/boot/dts/w1-gpio-overlay.dts
+++ b/arch/arm/boot/dts/w1-gpio-overlay.dts
@@ -1,4 +1,4 @@
-// Definitions for lirc-rpi module
+// Definitions for w1-gpio module (without external pullup)
/dts-v1/;
/plugin/;
@@ -14,6 +14,7 @@
pinctrl-names = "default";
pinctrl-0 = <&w1_pins>;
gpios = <&gpio 4 0>;
+ rpi,parasitic-power = <0>;
status = "okay";
};
};
@@ -33,5 +34,6 @@
__overrides__ {
gpiopin = <&w1>,"gpios:4",
<&w1_pins>,"brcm,pins:0";
+ pullup = <&w1>,"rpi,parasitic-power:0";
};
};
--- a/arch/arm/boot/dts/w1-gpio-pullup-overlay.dts
+++ b/arch/arm/boot/dts/w1-gpio-pullup-overlay.dts
@@ -1,4 +1,4 @@
-// Definitions for lirc-rpi module
+// Definitions for w1-gpio module (with external pullup)
/dts-v1/;
/plugin/;
@@ -14,6 +14,7 @@
pinctrl-names = "default";
pinctrl-0 = <&w1_pins>;
gpios = <&gpio 4 0>, <&gpio 5 1>;
+ rpi,parasitic-power = <0>;
status = "okay";
};
};
@@ -33,7 +34,8 @@
__overrides__ {
gpiopin = <&w1>,"gpios:4",
<&w1_pins>,"brcm,pins:0";
- pullup = <&w1>,"gpios:16",
+ extpullup = <&w1>,"gpios:16",
<&w1_pins>,"brcm,pins:4";
+ pullup = <&w1>,"rpi,parasitic-power:0";
};
};
--- a/drivers/w1/masters/w1-gpio.c
+++ b/drivers/w1/masters/w1-gpio.c
@@ -23,10 +23,14 @@
#include "../w1.h"
#include "../w1_int.h"
-static int w1_gpio_pullup = -1;
-static int w1_gpio_pullup_orig = -1;
+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, "GPIO pin pullup number");
+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);
@@ -99,6 +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)
@@ -107,6 +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)
@@ -122,7 +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;
@@ -158,17 +166,20 @@ static int w1_gpio_probe(struct platform
}
w1_gpio_pin_orig = pdata->pin;
- w1_gpio_pullup_orig = pdata->ext_pullup_enable_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;
}
- if(gpio_is_valid(w1_gpio_pullup)) {
- pdata->ext_pullup_enable_pin = w1_gpio_pullup;
+ 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, gpio pullup pin %d\n", pdata->pin, pdata->ext_pullup_enable_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) {
@@ -199,10 +210,10 @@ static int w1_gpio_probe(struct platform
master->set_pullup = w1_gpio_set_pullup;
}
- if (gpio_is_valid(w1_gpio_pullup)) {
+ if (pdata->parasitic_power) {
if (pdata->is_open_drain)
- printk(KERN_ERR "w1-gpio 'pullup' option "
- "doesn't work with open drain GPIO\n");
+ 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;
}
@@ -238,7 +249,8 @@ 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_orig;
+ pdata->ext_pullup_enable_pin = w1_gpio_pullup_pin_orig;
+ pdata->parasitic_power = w1_gpio_pullup_orig;
return 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;