[PATCH] w1: add DS2405 addressable switch driver

[Maciej S. Szmigiero]

This adds a driver for a DS2405 1-wire single-channel addressable switch.
The DS2405 can also work as a single-channel binary remote sensor.

This driver supports two attributes: "state" and "output" which are the
same attribute names as supported by existing DS2406, DS2408 and DS2413
drivers.

Signed-off-by: Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
---
 drivers/w1/slaves/Kconfig     |   8 ++
 drivers/w1/slaves/Makefile    |   1 +
 drivers/w1/slaves/w1_ds2405.c | 238 ++++++++++++++++++++++++++++++++++++++++++
 drivers/w1/w1_family.h        |   1 +
 drivers/w1/w1_io.c            |   1 +
 5 files changed, 249 insertions(+)
 create mode 100644 drivers/w1/slaves/w1_ds2405.c

diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
index cfe74d09932e..0ef9f2663dbd 100644
--- a/drivers/w1/slaves/Kconfig
+++ b/drivers/w1/slaves/Kconfig
@@ -16,6 +16,14 @@ 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_DS2405
+	tristate "DS2405 Addressable Switch"
+	help
+	  Say Y or M here if you want to use a DS2405 1-wire
+	  single-channel addressable switch.
+	  This device can also work as a single-channel
+	  binary remote sensor.
+
 config W1_SLAVE_DS2408
 	tristate "8-Channel Addressable Switch (IO Expander) 0x29 family support (DS2408)"
 	help
diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
index 1e9989afe7bf..b4a358955ef9 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-$(CONFIG_W1_SLAVE_DS2405)	+= w1_ds2405.o
 obj-$(CONFIG_W1_SLAVE_DS2408)	+= w1_ds2408.o
 obj-$(CONFIG_W1_SLAVE_DS2413)	+= w1_ds2413.o
 obj-$(CONFIG_W1_SLAVE_DS2406)	+= w1_ds2406.o
diff --git a/drivers/w1/slaves/w1_ds2405.c b/drivers/w1/slaves/w1_ds2405.c
new file mode 100644
index 000000000000..1f350cf2b6ec
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2405.c
@@ -0,0 +1,238 @@
+/*
+ *	w1_ds2405.c
+ *
+ * Copyright (c) 2017 Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
+ * Based on w1_therm.c copyright (c) 2004 Evgeniy Polyakov <zbr@xxxxxxxxxxx>
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the therms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/mutex.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include "../w1.h"
+#include "../w1_family.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Driver for 1-wire Dallas DS2405 PIO.");
+MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2405));
+
+static int w1_ds2405_select(struct w1_slave *sl, bool only_active)
+{
+	struct w1_master *dev = sl->master;
+
+	u64 dev_addr = le64_to_cpu(*(u64 *)&sl->reg_num);
+	unsigned int bit_ctr;
+
+	if (w1_reset_bus(dev) != 0)
+		return 0;
+
+	/*
+	 * We cannot use a normal Match ROM command
+	 * since doing so would toggle PIO state
+	 */
+	w1_write_8(dev, only_active ? W1_ALARM_SEARCH : W1_SEARCH);
+
+	for (bit_ctr = 0; bit_ctr < 64; bit_ctr++) {
+		int bit2send = !!(dev_addr & BIT(bit_ctr));
+		u8 ret;
+
+		ret = w1_triplet(dev, bit2send);
+
+		if ((ret & (BIT(0) | BIT(1))) ==
+		    (BIT(0) | BIT(1))) /* no devices found */
+			return 0;
+
+		if (!!(ret & BIT(2)) != bit2send)
+			/* wrong direction taken - no such device */
+			return 0;
+	}
+
+	return 1;
+}
+
+static int w1_ds2405_read_pio(struct w1_slave *sl)
+{
+	if (w1_ds2405_select(sl, true))
+		return 0; /* "active" means PIO is low */
+
+	if (w1_ds2405_select(sl, false))
+		return 1;
+
+	return -ENODEV;
+}
+
+static ssize_t state_show(struct device *device,
+			  struct device_attribute *attr, char *buf)
+{
+	struct w1_slave *sl = dev_to_w1_slave(device);
+	struct w1_master *dev = sl->master;
+
+	int ret;
+	ssize_t f_retval;
+	u8 state;
+
+	ret = mutex_lock_interruptible(&dev->bus_mutex);
+	if (ret)
+		return ret;
+
+	if (!w1_ds2405_select(sl, false)) {
+		f_retval = -ENODEV;
+		goto out_unlock;
+	}
+
+	state = w1_read_8(dev);
+	if (state != 0 &&
+	    state != 0xff) {
+		dev_err(device, "non-consistent state %x\n", state);
+		f_retval = -EIO;
+		goto out_unlock;
+	}
+
+	*buf = state ? '1' : '0';
+	f_retval = 1;
+
+out_unlock:
+	w1_reset_bus(dev);
+	mutex_unlock(&dev->bus_mutex);
+
+	return f_retval;
+}
+
+static ssize_t output_show(struct device *device,
+			   struct device_attribute *attr, char *buf)
+{
+	struct w1_slave *sl = dev_to_w1_slave(device);
+	struct w1_master *dev = sl->master;
+
+	int ret;
+	ssize_t f_retval;
+
+	ret = mutex_lock_interruptible(&dev->bus_mutex);
+	if (ret)
+		return ret;
+
+	ret = w1_ds2405_read_pio(sl);
+	if (ret < 0) {
+		f_retval = ret;
+		goto out_unlock;
+	}
+
+	*buf = ret ? '1' : '0';
+	f_retval = 1;
+
+out_unlock:
+	w1_reset_bus(dev);
+	mutex_unlock(&dev->bus_mutex);
+
+	return f_retval;
+}
+
+static ssize_t output_store(struct device *device,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct w1_slave *sl = dev_to_w1_slave(device);
+	struct w1_master *dev = sl->master;
+
+	int ret, current_pio;
+	unsigned int val;
+	ssize_t f_retval;
+
+	if (count < 1)
+		return -EINVAL;
+
+	if (sscanf(buf, " %u%n", &val, &ret) < 1)
+		return -EINVAL;
+
+	if (val != 0 && val != 1)
+		return -EINVAL;
+
+	f_retval = ret;
+
+	ret = mutex_lock_interruptible(&dev->bus_mutex);
+	if (ret)
+		return ret;
+
+	current_pio = w1_ds2405_read_pio(sl);
+	if (current_pio < 0) {
+		f_retval = current_pio;
+		goto out_unlock;
+	}
+
+	if (current_pio == val)
+		goto out_unlock;
+
+	if (w1_reset_bus(dev) != 0) {
+		f_retval = -ENODEV;
+		goto out_unlock;
+	}
+
+	/*
+	 * can't use w1_reset_select_slave() here since it uses Skip ROM if
+	 * there is only one device on bus
+	 */
+	do {
+		u64 dev_addr = le64_to_cpu(*(u64 *)&sl->reg_num);
+		u8 cmd[9];
+
+		cmd[0] = W1_MATCH_ROM;
+		memcpy(&cmd[1], &dev_addr, sizeof(dev_addr));
+
+		w1_write_block(dev, cmd, sizeof(cmd));
+	} while (0);
+
+out_unlock:
+	w1_reset_bus(dev);
+	mutex_unlock(&dev->bus_mutex);
+
+	return f_retval;
+}
+
+static DEVICE_ATTR_RO(state);
+static DEVICE_ATTR_RW(output);
+
+static struct attribute *w1_ds2405_attrs[] = {
+	&dev_attr_state.attr,
+	&dev_attr_output.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(w1_ds2405);
+
+static struct w1_family_ops w1_ds2405_fops = {
+	.groups = w1_ds2405_groups
+};
+
+static struct w1_family w1_family_ds2405 = {
+	.fid = W1_FAMILY_DS2405,
+	.fops = &w1_ds2405_fops
+};
+
+static int __init w1_ds2405_init(void)
+{
+	return w1_register_family(&w1_family_ds2405);
+}
+
+static void __exit w1_ds2405_fini(void)
+{
+	w1_unregister_family(&w1_family_ds2405);
+}
+
+module_init(w1_ds2405_init);
+module_exit(w1_ds2405_fini);
diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
index 10a7a0767187..66cb0d2fe049 100644
--- a/drivers/w1/w1_family.h
+++ b/drivers/w1/w1_family.h
@@ -30,6 +30,7 @@
 #define W1_FAMILY_BQ27000	0x01
 #define W1_FAMILY_SMEM_01	0x01
 #define W1_FAMILY_SMEM_81	0x81
+#define W1_FAMILY_DS2405	0x05
 #define W1_THERM_DS18S20 	0x10
 #define W1_FAMILY_DS28E04	0x1C
 #define W1_COUNTER_DS2423	0x1D
diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index f4bc8c100a01..a209869eff76 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -233,6 +233,7 @@ u8 w1_triplet(struct w1_master *dev, int bdir)
 		return retval;
 	}
 }
+EXPORT_SYMBOL_GPL(w1_triplet);
 
 /**
  * w1_read_8() - Reads 8 bits.