w1: add 1-wire (w1) DS2408 8-Channel Addressable Switch support [Linux 3.0]

This Linux kernel change "w1: add 1-wire (w1) DS2408 8-Channel Addressable Switch support" is included in the Linux 3.0 release. This change is authored by Jean-François Dagenais <dagenaisj [at] sonatest.com> on Thu May 26 16:26:02 2011 -0700. The commit for this change in Linux stable tree is 8961027 (patch).

w1: add 1-wire (w1) DS2408 8-Channel Addressable Switch support

This DS2408 w1 slave driver is not complete for all the features of the
chip, but its sufficient if you use it as a simple IO expander.

[randy.dunlap@oracle.com: fix w1_ds2408.c printk formats]
Signed-off-by: Jean-François Dagenais <dagenaisj@sonatest.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Cc: Matt Reimer <mreimer@vpop.net>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are 411 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/w1/slaves/Kconfig     |   7 +
 drivers/w1/slaves/Makefile    |   1 +
 drivers/w1/slaves/w1_ds2408.c | 402 ++++++++++++++++++++++++++++++++++++++++++
 drivers/w1/w1_family.h        |   1 +
 4 files changed, 411 insertions(+)
 create mode 100644 drivers/w1/slaves/w1_ds2408.c

diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
index f0c9096..cd1b724 100644
--- a/drivers/w1/slaves/Kconfig
+++ b/drivers/w1/slaves/Kconfig
@@ -16,6 +16,13 @@ config W1_SLAVE_SMEM
      Say Y here if you want to connect 1-wire
      simple 64bit memory rom(ds2401/ds2411/ds1990*) to your wire.

+config W1_SLAVE_DS2408
+        tristate "8-Channel Addressable Switch (IO Expander) 0x29 family support (DS2408)"
+        help
+          Say Y here if you want to use a 1-wire
+
+         DS2408 8-Channel Addressable Switch device support
+
 config W1_SLAVE_DS2423
    tristate "Counter 1-wire device (DS2423)"
    select CRC16
diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
index 3c76350..75e3913 100644
--- a/drivers/w1/slaves/Makefile
+++ b/drivers/w1/slaves/Makefile
@@ -4,6 +4,7 @@

 obj-$(CONFIG_W1_SLAVE_THERM)   += w1_therm.o
 obj-$(CONFIG_W1_SLAVE_SMEM)    += w1_smem.o
+obj-$(CONFIG_W1_SLAVE_DS2408)   += w1_ds2408.o
 obj-$(CONFIG_W1_SLAVE_DS2423)  += w1_ds2423.o
 obj-$(CONFIG_W1_SLAVE_DS2431)  += w1_ds2431.o
 obj-$(CONFIG_W1_SLAVE_DS2433)  += w1_ds2433.o
diff --git a/drivers/w1/slaves/w1_ds2408.c b/drivers/w1/slaves/w1_ds2408.c
new file mode 100644
index 0000000..c377818
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2408.c
@@ -0,0 +1,402 @@
+/*
+ * w1_ds2408.c - w1 family 29 (DS2408) driver
+ *
+ * Copyright (c) 2010 Jean-Francois Dagenais <dagenaisj@sonatest.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/device.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_family.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jean-Francois Dagenais <dagenaisj@sonatest.com>");
+MODULE_DESCRIPTION("w1 family 29 driver for DS2408 8 Pin IO");
+
+
+#define W1_F29_RETRIES     3
+
+#define W1_F29_REG_LOGIG_STATE             0x88 /* R */
+#define W1_F29_REG_OUTPUT_LATCH_STATE      0x89 /* R */
+#define W1_F29_REG_ACTIVITY_LATCH_STATE    0x8A /* R */
+#define W1_F29_REG_COND_SEARCH_SELECT_MASK 0x8B /* RW */
+#define W1_F29_REG_COND_SEARCH_POL_SELECT  0x8C /* RW */
+#define W1_F29_REG_CONTROL_AND_STATUS      0x8D /* RW */
+
+#define W1_F29_FUNC_READ_PIO_REGS          0xF0
+#define W1_F29_FUNC_CHANN_ACCESS_READ      0xF5
+#define W1_F29_FUNC_CHANN_ACCESS_WRITE     0x5A
+/* also used to write the control/status reg (0x8D): */
+#define W1_F29_FUNC_WRITE_COND_SEARCH_REG  0xCC
+#define W1_F29_FUNC_RESET_ACTIVITY_LATCHES 0xC3
+
+#define W1_F29_SUCCESS_CONFIRM_BYTE        0xAA
+
+static int _read_reg(struct w1_slave *sl, u8 address, unsigned char* buf)
+{
+   u8 wrbuf[3];
+   dev_dbg(&sl->dev,
+           "Reading with slave: %p, reg addr: %0#4x, buff addr: %p",
+           sl, (unsigned int)address, buf);
+
+   if (!buf)
+       return -EINVAL;
+
+   mutex_lock(&sl->master->mutex);
+   dev_dbg(&sl->dev, "mutex locked");
+
+   if (w1_reset_select_slave(sl)) {
+       mutex_unlock(&sl->master->mutex);
+       return -EIO;
+   }
+
+   wrbuf[0] = W1_F29_FUNC_READ_PIO_REGS;
+   wrbuf[1] = address;
+   wrbuf[2] = 0;
+   w1_write_block(sl->master, wrbuf, 3);
+   *buf = w1_read_8(sl->master);
+
+   mutex_unlock(&sl->master->mutex);
+   dev_dbg(&sl->dev, "mutex unlocked");
+   return 1;
+}
+
+static ssize_t w1_f29_read_state(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   dev_dbg(&kobj_to_w1_slave(kobj)->dev,
+       "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
+       bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
+   if (count != 1 || off != 0)
+       return -EFAULT;
+   return _read_reg(kobj_to_w1_slave(kobj), W1_F29_REG_LOGIG_STATE, buf);
+}
+
+static ssize_t w1_f29_read_output(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   dev_dbg(&kobj_to_w1_slave(kobj)->dev,
+       "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
+       bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
+   if (count != 1 || off != 0)
+       return -EFAULT;
+   return _read_reg(kobj_to_w1_slave(kobj),
+                    W1_F29_REG_OUTPUT_LATCH_STATE, buf);
+}
+
+static ssize_t w1_f29_read_activity(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   dev_dbg(&kobj_to_w1_slave(kobj)->dev,
+       "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
+       bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
+   if (count != 1 || off != 0)
+       return -EFAULT;
+   return _read_reg(kobj_to_w1_slave(kobj),
+                    W1_F29_REG_ACTIVITY_LATCH_STATE, buf);
+}
+
+static ssize_t w1_f29_read_cond_search_mask(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   dev_dbg(&kobj_to_w1_slave(kobj)->dev,
+       "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
+       bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
+   if (count != 1 || off != 0)
+       return -EFAULT;
+   return _read_reg(kobj_to_w1_slave(kobj),
+       W1_F29_REG_COND_SEARCH_SELECT_MASK, buf);
+}
+
+static ssize_t w1_f29_read_cond_search_polarity(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   if (count != 1 || off != 0)
+       return -EFAULT;
+   return _read_reg(kobj_to_w1_slave(kobj),
+       W1_F29_REG_COND_SEARCH_POL_SELECT, buf);
+}
+
+static ssize_t w1_f29_read_status_control(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   if (count != 1 || off != 0)
+       return -EFAULT;
+   return _read_reg(kobj_to_w1_slave(kobj),
+       W1_F29_REG_CONTROL_AND_STATUS, buf);
+}
+
+
+
+
+static ssize_t w1_f29_write_output(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   struct w1_slave *sl = kobj_to_w1_slave(kobj);
+   u8 w1_buf[3];
+   u8 readBack;
+   unsigned int retries = W1_F29_RETRIES;
+
+   if (count != 1 || off != 0)
+       return -EFAULT;
+
+   dev_dbg(&sl->dev, "locking mutex for write_output");
+   mutex_lock(&sl->master->mutex);
+   dev_dbg(&sl->dev, "mutex locked");
+
+   if (w1_reset_select_slave(sl))
+       goto error;
+
+   while (retries--) {
+       w1_buf[0] = W1_F29_FUNC_CHANN_ACCESS_WRITE;
+       w1_buf[1] = *buf;
+       w1_buf[2] = ~(*buf);
+       w1_write_block(sl->master, w1_buf, 3);
+
+       readBack = w1_read_8(sl->master);
+       /* here the master could read another byte which
+          would be the PIO reg (the actual pin logic state)
+          since in this driver we don't know which pins are
+          in and outs, there's no value to read the state and
+          compare. with (*buf) so end this command abruptly: */
+       if (w1_reset_resume_command(sl->master))
+           goto error;
+
+       if (readBack != 0xAA) {
+           /* try again, the slave is ready for a command */
+           continue;
+       }
+
+       /* go read back the output latches */
+       /* (the direct effect of the write above) */
+       w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
+       w1_buf[1] = W1_F29_REG_OUTPUT_LATCH_STATE;
+       w1_buf[2] = 0;
+       w1_write_block(sl->master, w1_buf, 3);
+       /* read the result of the READ_PIO_REGS command */
+       if (w1_read_8(sl->master) == *buf) {
+           /* success! */
+           mutex_unlock(&sl->master->mutex);
+           dev_dbg(&sl->dev,
+               "mutex unlocked, retries:%d", retries);
+           return 1;
+       }
+   }
+error:
+   mutex_unlock(&sl->master->mutex);
+   dev_dbg(&sl->dev, "mutex unlocked in error, retries:%d", retries);
+
+   return -EIO;
+}
+
+
+/**
+ * Writing to the activity file resets the activity latches.
+ */
+static ssize_t w1_f29_write_activity(
+   struct file *filp, struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf, loff_t off, size_t count)
+{
+   struct w1_slave *sl = kobj_to_w1_slave(kobj);
+   unsigned int retries = W1_F29_RETRIES;
+
+   if (count != 1 || off != 0)
+       return -EFAULT;
+
+   mutex_lock(&sl->master->mutex);
+
+   if (w1_reset_select_slave(sl))
+       goto error;
+
+   while (retries--) {
+       w1_write_8(sl->master, W1_F29_FUNC_RESET_ACTIVITY_LATCHES);
+       if (w1_read_8(sl->master) == W1_F29_SUCCESS_CONFIRM_BYTE) {
+           mutex_unlock(&sl->master->mutex);
+           return 1;
+       }
+       if (w1_reset_resume_command(sl->master))
+           goto error;
+   }
+
+error:
+   mutex_unlock(&sl->master->mutex);
+   return -EIO;
+}
+
+static ssize_t w1_f29_write_status_control(
+   struct file *filp,
+   struct kobject *kobj,
+   struct bin_attribute *bin_attr,
+   char *buf,
+   loff_t off,
+   size_t count)
+{
+   struct w1_slave *sl = kobj_to_w1_slave(kobj);
+   u8 w1_buf[4];
+   unsigned int retries = W1_F29_RETRIES;
+
+   if (count != 1 || off != 0)
+       return -EFAULT;
+
+   mutex_lock(&sl->master->mutex);
+
+   if (w1_reset_select_slave(sl))
+       goto error;
+
+   while (retries--) {
+       w1_buf[0] = W1_F29_FUNC_WRITE_COND_SEARCH_REG;
+       w1_buf[1] = W1_F29_REG_CONTROL_AND_STATUS;
+       w1_buf[2] = 0;
+       w1_buf[3] = *buf;
+
+       w1_write_block(sl->master, w1_buf, 4);
+       if (w1_reset_resume_command(sl->master))
+           goto error;
+
+       w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
+       w1_buf[1] = W1_F29_REG_CONTROL_AND_STATUS;
+       w1_buf[2] = 0;
+
+       w1_write_block(sl->master, w1_buf, 3);
+       if (w1_read_8(sl->master) == *buf) {
+           /* success! */
+           mutex_unlock(&sl->master->mutex);
+           return 1;
+       }
+   }
+error:
+   mutex_unlock(&sl->master->mutex);
+
+   return -EIO;
+}
+
+
+
+#define NB_SYSFS_BIN_FILES 6
+static struct bin_attribute w1_f29_sysfs_bin_files[NB_SYSFS_BIN_FILES] = {
+   {
+       .attr = {
+           .name = "state",
+           .mode = S_IRUGO,
+       },
+       .size = 1,
+       .read = w1_f29_read_state,
+   },
+   {
+       .attr = {
+           .name = "output",
+           .mode = S_IRUGO | S_IWUSR | S_IWGRP,
+       },
+       .size = 1,
+       .read = w1_f29_read_output,
+       .write = w1_f29_write_output,
+   },
+   {
+       .attr = {
+           .name = "activity",
+           .mode = S_IRUGO,
+       },
+       .size = 1,
+       .read = w1_f29_read_activity,
+       .write = w1_f29_write_activity,
+   },
+   {
+       .attr = {
+           .name = "cond_search_mask",
+           .mode = S_IRUGO,
+       },
+       .size = 1,
+       .read = w1_f29_read_cond_search_mask,
+       .write = 0,
+   },
+   {
+       .attr = {
+           .name = "cond_search_polarity",
+           .mode = S_IRUGO,
+       },
+       .size = 1,
+       .read = w1_f29_read_cond_search_polarity,
+       .write = 0,
+   },
+   {
+       .attr = {
+           .name = "status_control",
+           .mode = S_IRUGO | S_IWUSR | S_IWGRP,
+       },
+       .size = 1,
+       .read = w1_f29_read_status_control,
+       .write = w1_f29_write_status_control,
+   }
+};
+
+static int w1_f29_add_slave(struct w1_slave *sl)
+{
+   int err = 0;
+   int i;
+
+   for (i = 0; i < NB_SYSFS_BIN_FILES && !err; ++i)
+       err = sysfs_create_bin_file(
+           &sl->dev.kobj,
+           &(w1_f29_sysfs_bin_files[i]));
+   if (err)
+       while (--i >= 0)
+           sysfs_remove_bin_file(&sl->dev.kobj,
+               &(w1_f29_sysfs_bin_files[i]));
+   return err;
+}
+
+static void w1_f29_remove_slave(struct w1_slave *sl)
+{
+   int i;
+   for (i = NB_SYSFS_BIN_FILES; i <= 0; --i)
+       sysfs_remove_bin_file(&sl->dev.kobj,
+           &(w1_f29_sysfs_bin_files[i]));
+}
+
+static struct w1_family_ops w1_f29_fops = {
+   .add_slave      = w1_f29_add_slave,
+   .remove_slave   = w1_f29_remove_slave,
+};
+
+static struct w1_family w1_family_29 = {
+   .fid = W1_FAMILY_DS2408,
+   .fops = &w1_f29_fops,
+};
+
+static int __init w1_f29_init(void)
+{
+   return w1_register_family(&w1_family_29);
+}
+
+static void __exit w1_f29_exit(void)
+{
+   w1_unregister_family(&w1_family_29);
+}
+
+module_init(w1_f29_init);
+module_exit(w1_f29_exit);
diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
index f3b636d..7513759 100644
--- a/drivers/w1/w1_family.h
+++ b/drivers/w1/w1_family.h
@@ -34,6 +34,7 @@
 #define W1_THERM_DS1822    0x22
 #define W1_EEPROM_DS2433   0x23
 #define W1_THERM_DS18B20   0x28
+#define W1_FAMILY_DS2408   0x29
 #define W1_EEPROM_DS2431   0x2D
 #define W1_FAMILY_DS2760   0x30

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