[PATCH 4/5] 1-wire: add ds2431 support

[Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>]

Based on linux implementation.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
---
 drivers/w1/slaves/Kconfig     |   10 ++
 drivers/w1/slaves/Makefile    |    1 +
 drivers/w1/slaves/w1_ds2431.c |  294 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 305 insertions(+)
 create mode 100644 drivers/w1/slaves/w1_ds2431.c

diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
index f35eedf..26150a2 100644
--- a/drivers/w1/slaves/Kconfig
+++ b/drivers/w1/slaves/Kconfig
@@ -4,4 +4,14 @@
 
 menu "1-wire Slaves"
 
+config W1_SLAVE_DS2431
+	bool "1kb EEPROM family support (DS2431)"
+	help
+	  Say Y here if you want to use a 1-wire
+	  1kb EEPROM family device (DS2431)
+
+config W1_SLAVE_DS2431_WRITE
+	bool "write support"
+	depends on W1_SLAVE_DS2431
+
 endmenu
diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
index ac9a5a7..65804e0 100644
--- a/drivers/w1/slaves/Makefile
+++ b/drivers/w1/slaves/Makefile
@@ -2,3 +2,4 @@
 # Makefile for the Dallas's 1-wire slaves.
 #
 
+obj-$(CONFIG_W1_SLAVE_DS2431)	+= w1_ds2431.o
diff --git a/drivers/w1/slaves/w1_ds2431.c b/drivers/w1/slaves/w1_ds2431.c
new file mode 100644
index 0000000..30e6e1d
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2431.c
@@ -0,0 +1,294 @@
+/*
+ * w1_ds2431.c - w1 family 2d (DS2431) driver
+ *
+ * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
+ * Copyright (c) 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
+ *
+ * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <init.h>
+#include "../w1.h"
+
+#define W1_F2D_EEPROM_SIZE	128
+#define W1_F2D_PAGE_COUNT	4
+#define W1_F2D_PAGE_BITS	5
+#define W1_F2D_PAGE_SIZE	(1 << W1_F2D_PAGE_BITS)
+#define W1_F2D_PAGE_MASK	0x1F
+
+#define W1_F2D_SCRATCH_BITS	3
+#define W1_F2D_SCRATCH_SIZE	(1 << W1_F2D_SCRATCH_BITS)
+#define W1_F2D_SCRATCH_MASK 	(W1_F2D_SCRATCH_SIZE - 1)
+
+#define W1_F2D_READ_EEPROM	0xF0
+#define W1_F2D_WRITE_SCRATCH	0x0F
+#define W1_F2D_READ_SCRATCH	0xAA
+#define W1_F2D_COPY_SCRATCH	0x55
+
+
+#define W1_F2D_TPROG_MS		11
+
+#define W1_F2D_READ_RETRIES	10
+#define W1_F2D_READ_MAXLEN	8
+
+#define DRIVERNAME	"ds2431"
+
+static int ds2431_count = 0;
+
+/*
+ * Check the file size bounds and adjusts count as needed.
+ * This would not be needed if the file size didn't reset to 0 after a write.
+ */
+static inline size_t ds2431_fix_count(loff_t off, size_t count, size_t size)
+{
+	if (off > size)
+		return 0;
+
+	if ((off + count) > size)
+		return size - off;
+
+	return count;
+}
+
+/*
+ * Read a block from W1 ROM two times and compares the results.
+ * If they are equal they are returned, otherwise the read
+ * is repeated W1_F2D_READ_RETRIES times.
+ *
+ * count must not exceed W1_F2D_READ_MAXLEN.
+ */
+int ds2431_readblock(struct w1_device *dev, int off, int count, char *buf)
+{
+	struct w1_bus *bus = dev->bus;
+	u8 wrbuf[3];
+	u8 cmp[W1_F2D_READ_MAXLEN];
+	int tries = W1_F2D_READ_RETRIES;
+
+	do {
+		wrbuf[0] = W1_F2D_READ_EEPROM;
+		wrbuf[1] = off & 0xff;
+		wrbuf[2] = off >> 8;
+
+		if (w1_reset_select_slave(dev))
+			return -1;
+
+		w1_write_block(bus, wrbuf, 3);
+		w1_read_block(bus, buf, count);
+
+		if (w1_reset_select_slave(dev))
+			return -1;
+
+		w1_write_block(bus, wrbuf, 3);
+		w1_read_block(bus, cmp, count);
+
+		if (!memcmp(cmp, buf, count))
+			return 0;
+	} while (--tries);
+
+	dev_err(&dev->dev, "proof reading failed %d times\n",
+			W1_F2D_READ_RETRIES);
+
+	return -1;
+}
+
+static ssize_t ds2431_cdev_read(struct cdev *cdev, void *buf, size_t count,
+		loff_t off, ulong flags)
+{
+	struct w1_device *dev = cdev->priv;
+	int todo = count;
+
+	count = ds2431_fix_count(off, count, W1_F2D_EEPROM_SIZE);
+	if (count == 0)
+		return 0;
+
+	/* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
+	while (todo > 0) {
+		int block_read;
+
+		if (todo >= W1_F2D_READ_MAXLEN)
+			block_read = W1_F2D_READ_MAXLEN;
+		else
+			block_read = todo;
+
+		if (ds2431_readblock(dev, off, block_read, buf) < 0)
+			count = -EIO;
+
+		todo -= W1_F2D_READ_MAXLEN;
+		buf += W1_F2D_READ_MAXLEN;
+		off += W1_F2D_READ_MAXLEN;
+	}
+
+	return count;
+}
+
+#ifdef CONFIG_W1_SLAVE_DS2431_WRITE
+/*
+ * Writes to the scratchpad and reads it back for verification.
+ * Then copies the scratchpad to EEPROM.
+ * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
+ * must be W1_F2D_SCRATCH_SIZE bytes long.
+ * The master must be locked.
+ *
+ * @param sl	The slave structure
+ * @param addr	Address for the write
+ * @param len   length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
+ * @param data	The data to write
+ * @return	0=Success -1=failure
+ */
+static int ds2431_write(struct w1_device *dev, int addr, int len, const u8 *data)
+{
+	struct w1_bus *bus = dev->bus;
+	int tries = W1_F2D_READ_RETRIES;
+	u8 wrbuf[4];
+	u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
+	u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
+
+retry:
+
+	/* Write the data to the scratchpad */
+	if (w1_reset_select_slave(dev))
+		return -1;
+
+	wrbuf[0] = W1_F2D_WRITE_SCRATCH;
+	wrbuf[1] = addr & 0xff;
+	wrbuf[2] = addr >> 8;
+
+	w1_write_block(bus, wrbuf, 3);
+	w1_write_block(bus, data, len);
+
+	/* Read the scratchpad and verify */
+	if (w1_reset_select_slave(dev))
+		return -1;
+
+	w1_write_8(bus, W1_F2D_READ_SCRATCH);
+	w1_read_block(bus, rdbuf, len + 3);
+
+	/* Compare what was read against the data written */
+	if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
+	    (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
+
+		if (--tries)
+			goto retry;
+
+		dev_err(&dev->dev,
+			"could not write to eeprom, scratchpad compare failed %d times\n",
+			W1_F2D_READ_RETRIES);
+
+		return -1;
+	}
+
+	/* Copy the scratchpad to EEPROM */
+	if (w1_reset_select_slave(dev))
+		return -1;
+
+	wrbuf[0] = W1_F2D_COPY_SCRATCH;
+	wrbuf[3] = es;
+	w1_write_block(bus, wrbuf, 4);
+
+	/* Sleep for tprog ms to wait for the write to complete */
+	mdelay(W1_F2D_TPROG_MS);
+
+	/* Reset the bus to wake up the EEPROM  */
+	w1_reset_bus(bus);
+
+	return 0;
+}
+
+static ssize_t ds2431_cdev_write(struct cdev *cdev, const void *buf, size_t count,
+		loff_t off, ulong flags)
+{
+	struct w1_device *dev = cdev->priv;
+	int addr, len;
+	int copy;
+
+	count = ds2431_fix_count(off, count, W1_F2D_EEPROM_SIZE);
+	if (count == 0)
+		return 0;
+
+	/* Can only write data in blocks of the size of the scratchpad */
+	addr = off;
+	len = count;
+	while (len > 0) {
+
+		/* if len too short or addr not aligned */
+		if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
+			char tmp[W1_F2D_SCRATCH_SIZE];
+
+			/* read the block and update the parts to be written */
+			if (ds2431_readblock(dev, addr & ~W1_F2D_SCRATCH_MASK,
+					W1_F2D_SCRATCH_SIZE, tmp)) {
+				count = -EIO;
+				goto out_up;
+			}
+
+			/* copy at most to the boundary of the PAGE or len */
+			copy = W1_F2D_SCRATCH_SIZE -
+				(addr & W1_F2D_SCRATCH_MASK);
+
+			if (copy > len)
+				copy = len;
+
+			memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
+			if (ds2431_write(dev, addr & ~W1_F2D_SCRATCH_MASK,
+					W1_F2D_SCRATCH_SIZE, tmp) < 0) {
+				count = -EIO;
+				goto out_up;
+			}
+		} else {
+
+			copy = W1_F2D_SCRATCH_SIZE;
+			if (ds2431_write(dev, addr, copy, buf) < 0) {
+				count = -EIO;
+				goto out_up;
+			}
+		}
+		buf += copy;
+		addr += copy;
+		len -= copy;
+	}
+
+out_up:
+	return count;
+}
+#else
+#define ds2431_cdev_write NULL
+#endif
+
+static struct file_operations ds2431_ops = {
+	.read	= ds2431_cdev_read,
+	.write	= ds2431_cdev_write,
+	.lseek	= dev_lseek_default,
+};
+
+static int ds2431_probe(struct w1_device *dev)
+{
+	struct cdev *cdev;
+
+	cdev = xzalloc(sizeof(*cdev));
+	cdev->dev	= &dev->dev;
+	cdev->priv	= dev;
+	cdev->ops	= &ds2431_ops;
+	cdev->size	= W1_F2D_EEPROM_SIZE;
+	cdev->name	= asprintf(DRIVERNAME"%d", ds2431_count++);
+	if (cdev->name == NULL)
+		return -ENOMEM;
+
+	return devfs_create(cdev);
+}
+
+struct w1_driver ds2431_driver = {
+	.drv = {
+		.name = DRIVERNAME,
+	},
+	.probe		= ds2431_probe,
+	.fid		= 0x2d,
+};
+
+static int w1_ds2431_init(void)
+{
+	return w1_driver_register(&ds2431_driver);
+}
+device_initcall(w1_ds2431_init);
-- 
1.7.10.4


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