drivers: w1: Add 1w slave driver for DS28E05 EEPROM

Add a one wire driver for the DS28E05 one wire slave chip. This chip
requires OverDrive support to talk to it.

Signed-off-by: Andrew Worsley <amworsley@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 313 insertions, 0 deletions

diff --git a/drivers/w1/slaves/w1_ds2805.c b/drivers/w1/slaves/w1_ds2805.c
new file mode 100644
index 000000000000..29348d283a65
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2805.c
@@ -0,0 +1,313 @@
+/*
+ * w1_ds2805 - w1 family 0d (DS28E05) driver
+ *
+ * Copyright (c) 2016 Andrew Worsley amworsley@gmail.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/w1.h>
+
+#define W1_EEPROM_DS2805       0x0D
+
+#define W1_F0D_EEPROM_SIZE		128
+#define W1_F0D_PAGE_BITS		3
+#define W1_F0D_PAGE_SIZE		(1<<W1_F0D_PAGE_BITS)
+#define W1_F0D_PAGE_MASK		0x0F
+
+#define W1_F0D_SCRATCH_BITS  1
+#define W1_F0D_SCRATCH_SIZE  (1<<W1_F0D_SCRATCH_BITS)
+#define W1_F0D_SCRATCH_MASK  (W1_F0D_SCRATCH_SIZE-1)
+
+#define W1_F0D_READ_EEPROM	0xF0
+#define W1_F0D_WRITE_EEPROM	0x55
+#define W1_F0D_RELEASE		0xFF
+
+#define W1_F0D_CS_OK		0xAA /* Chip Status Ok */
+
+#define W1_F0D_TPROG_MS		16
+
+#define W1_F0D_READ_RETRIES		10
+#define W1_F0D_READ_MAXLEN		W1_F0D_EEPROM_SIZE
+
+/*
+ * 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 w1_f0d_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_F0D_READ_RETRIES times.
+ *
+ * count must not exceed W1_F0D_READ_MAXLEN.
+ */
+static int w1_f0d_readblock(struct w1_slave *sl, int off, int count, char *buf)
+{
+	u8 wrbuf[3];
+	u8 cmp[W1_F0D_READ_MAXLEN];
+	int tries = W1_F0D_READ_RETRIES;
+
+	do {
+		wrbuf[0] = W1_F0D_READ_EEPROM;
+		wrbuf[1] = off & 0x7f;
+		wrbuf[2] = 0;
+
+		if (w1_reset_select_slave(sl))
+			return -1;
+
+		w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
+		w1_read_block(sl->master, buf, count);
+
+		if (w1_reset_select_slave(sl))
+			return -1;
+
+		w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
+		w1_read_block(sl->master, cmp, count);
+
+		if (!memcmp(cmp, buf, count))
+			return 0;
+	} while (--tries);
+
+	dev_err(&sl->dev, "proof reading failed %d times\n",
+			W1_F0D_READ_RETRIES);
+
+	return -1;
+}
+
+static ssize_t w1_f0d_read_bin(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);
+	int todo = count;
+
+	count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
+	if (count == 0)
+		return 0;
+
+	mutex_lock(&sl->master->mutex);
+
+	/* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
+	while (todo > 0) {
+		int block_read;
+
+		if (todo >= W1_F0D_READ_MAXLEN)
+			block_read = W1_F0D_READ_MAXLEN;
+		else
+			block_read = todo;
+
+		if (w1_f0d_readblock(sl, off, block_read, buf) < 0) {
+			count = -EIO;
+			break;
+		}
+
+		todo -= W1_F0D_READ_MAXLEN;
+		buf += W1_F0D_READ_MAXLEN;
+		off += W1_F0D_READ_MAXLEN;
+	}
+
+	mutex_unlock(&sl->master->mutex);
+
+	return count;
+}
+
+/*
+ * Writes to the scratchpad and reads it back for verification.
+ * Then copies the scratchpad to EEPROM.
+ * The data must be aligned at W1_F0D_SCRATCH_SIZE bytes and
+ * must be W1_F0D_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_F0D_PAGE_SIZE - (addr & W1_F0D_PAGE_MASK))
+ * @param data	The data to write
+ * @return	0=Success -1=failure
+ */
+static int w1_f0d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
+{
+	int tries = W1_F0D_READ_RETRIES;
+	u8 wrbuf[3];
+	u8 rdbuf[W1_F0D_SCRATCH_SIZE];
+	u8 cs;
+
+	if ((addr & 1) || (len != 2)) {
+		dev_err(&sl->dev, "%s: bad addr/len -  addr=%#x len=%d\n",
+		    __func__, addr, len);
+		return -1;
+	}
+
+retry:
+
+	/* Write the data to the scratchpad */
+	if (w1_reset_select_slave(sl))
+		return -1;
+
+	wrbuf[0] = W1_F0D_WRITE_EEPROM;
+	wrbuf[1] = addr & 0xff;
+	wrbuf[2] = 0xff; /* ?? from Example */
+
+	w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
+	w1_write_block(sl->master, data, len);
+
+	w1_read_block(sl->master, rdbuf, sizeof(rdbuf));
+	/* Compare what was read against the data written */
+	if ((rdbuf[0] != data[0]) || (rdbuf[1] != data[1])) {
+
+		if (--tries)
+			goto retry;
+
+		dev_err(&sl->dev,
+			"could not write to eeprom, scratchpad compare failed %d times\n",
+			W1_F0D_READ_RETRIES);
+		pr_info("%s: rdbuf = %#x %#x data = %#x %#x\n",
+		    __func__, rdbuf[0], rdbuf[1], data[0], data[1]);
+
+		return -1;
+	}
+
+	/* Trigger write out to EEPROM */
+	w1_write_8(sl->master, W1_F0D_RELEASE);
+
+	/* Sleep for tprog ms to wait for the write to complete */
+	msleep(W1_F0D_TPROG_MS);
+
+	/* Check CS (Command Status) == 0xAA ? */
+	cs = w1_read_8(sl->master);
+	if (cs != W1_F0D_CS_OK) {
+		dev_err(&sl->dev, "save to eeprom failed = CS=%#x\n", cs);
+		return -1;
+	}
+
+	return 0;
+}
+
+static ssize_t w1_f0d_write_bin(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);
+	int addr, len;
+	int copy;
+
+	count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
+	if (count == 0)
+		return 0;
+
+	mutex_lock(&sl->master->mutex);
+
+	/* 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_F0D_SCRATCH_SIZE || addr & W1_F0D_SCRATCH_MASK) {
+			char tmp[W1_F0D_SCRATCH_SIZE];
+
+			/* read the block and update the parts to be written */
+			if (w1_f0d_readblock(sl, addr & ~W1_F0D_SCRATCH_MASK,
+					W1_F0D_SCRATCH_SIZE, tmp)) {
+				count = -EIO;
+				goto out_up;
+			}
+
+			/* copy at most to the boundary of the PAGE or len */
+			copy = W1_F0D_SCRATCH_SIZE -
+				(addr & W1_F0D_SCRATCH_MASK);
+
+			if (copy > len)
+				copy = len;
+
+			memcpy(&tmp[addr & W1_F0D_SCRATCH_MASK], buf, copy);
+			if (w1_f0d_write(sl, addr & ~W1_F0D_SCRATCH_MASK,
+					W1_F0D_SCRATCH_SIZE, tmp) < 0) {
+				count = -EIO;
+				goto out_up;
+			}
+		} else {
+
+			copy = W1_F0D_SCRATCH_SIZE;
+			if (w1_f0d_write(sl, addr, copy, buf) < 0) {
+				count = -EIO;
+				goto out_up;
+			}
+		}
+		buf += copy;
+		addr += copy;
+		len -= copy;
+	}
+
+out_up:
+	mutex_unlock(&sl->master->mutex);
+
+	return count;
+}
+
+static struct bin_attribute w1_f0d_bin_attr = {
+	.attr = {
+		.name = "eeprom",
+		.mode = S_IRUGO | S_IWUSR,
+	},
+	.size = W1_F0D_EEPROM_SIZE,
+	.read = w1_f0d_read_bin,
+	.write = w1_f0d_write_bin,
+};
+
+static int w1_f0d_add_slave(struct w1_slave *sl)
+{
+	return sysfs_create_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
+}
+
+static void w1_f0d_remove_slave(struct w1_slave *sl)
+{
+	sysfs_remove_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
+}
+
+static struct w1_family_ops w1_f0d_fops = {
+	.add_slave      = w1_f0d_add_slave,
+	.remove_slave   = w1_f0d_remove_slave,
+};
+
+static struct w1_family w1_family_2d = {
+	.fid = W1_EEPROM_DS2805,
+	.fops = &w1_f0d_fops,
+};
+
+static int __init w1_f0d_init(void)
+{
+	pr_info("%s()\n", __func__);
+	return w1_register_family(&w1_family_2d);
+}
+
+static void __exit w1_f0d_fini(void)
+{
+	pr_info("%s()\n", __func__);
+	w1_unregister_family(&w1_family_2d);
+}
+
+module_init(w1_f0d_init);
+module_exit(w1_f0d_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Andrew Worsley amworsley@gmail.com");
+MODULE_DESCRIPTION("w1 family 0d driver for DS2805, 1kb EEPROM");