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

diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
index a373ae69d9f6ef8a5925dbd5004cd5e9b8fc5c05..080e5976e2a6b75965ed753ddf29648cb0b2f000 100644 (file)
--- 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 platform_device *pdev)
        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 platform_device *pdev)
        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 platform_device *pdev)
        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 platform_device *pdev)
 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_device *pdev)
                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_device *pdev)
                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 platform_device *pdev)
 
        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;
 }
 

diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index 129895f562b06630b464f2579dc9e5bdc105f35e..737a75b594c69716eae8d37479a40031b3045494 100644 (file)
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -173,6 +173,12 @@ 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);
 };

diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index 20f766afa4c7d7b8116565687541f84184fe61f4..c4fbdb1f25e961f9f7bacbac7b52a6d74cabaf12 100644 (file)
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -122,6 +122,20 @@ int w1_add_master_device(struct w1_bus_master *master)
                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). */

diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index f4bc8c100a01b1f04a62ebca2528c51c05f40520..77527e37c7e749754cd3dc2241cdcb64f178166c 100644 (file)
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -134,10 +134,22 @@ static void w1_pre_write(struct w1_master *dev)
 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;
        }
 }

diff --git a/include/linux/w1-gpio.h b/include/linux/w1-gpio.h
index d58594a3232492e33f1dd4babd3798b03e0f0203..feae94256256316fd9d850c3d83325af803fb2ce 100644 (file)
--- 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;