w1: complete eeprom low-level support

This completes w1-eeproom.c with the complete API. The provided test
commands allow to read and write any size at any offset (the low-level
code manages cross-page reads and writes. The following examples
modify a pre-written eeprom, which I host in an external socket of
my SPEC card:

   wrc# w1r 0 4
   read(0x0, 4): result = 4
   offset    0 (0x000): 240 (0xf0)
   offset    1 (0x001): 241 (0xf1)
   offset    2 (0x002): 242 (0xf2)
   offset    3 (0x003): 243 (0xf3)

   wrc# w1w 0 40 41 42
   offset    0 (0x000):  40 (0x28)
   offset    1 (0x001):  41 (0x29)
   offset    2 (0x002):  42 (0x2a)
   write(0x0, 3): result = 3

   wrc# w1r 0 4
   read(0x0, 4): result = 4
   offset    0 (0x000):  40 (0x28)
   offset    1 (0x001):  41 (0x29)
   offset    2 (0x002):  42 (0x2a)
   offset    3 (0x003): 243 (0xf3)

   wrc# w1r 30 4
   read(0x1e, 4): result = 4
   offset   30 (0x01e):  69 (0x45)
   offset   31 (0x01f):  70 (0x46)
   offset   32 (0x020):  71 (0x47)
   offset   33 (0x021):  72 (0x48)

   wrc# w1w 30 11 22 33 44 55 66
   offset   30 (0x01e):  11 (0x0b)
   offset   31 (0x01f):  22 (0x16)
   offset   32 (0x020):  33 (0x21)
   offset   33 (0x021):  44 (0x2c)
   offset   34 (0x022):  55 (0x37)
   offset   35 (0x023):  66 (0x42)
   write(0x1e, 6): result = 6

   wrc# w1r 30 6
   read(0x1e, 6): result = 6
   offset   30 (0x01e):  11 (0x0b)
   offset   31 (0x01f):  22 (0x16)
   offset   32 (0x020):  33 (0x21)
   offset   33 (0x021):  44 (0x2c)
   offset   34 (0x022):  55 (0x37)
   offset   35 (0x023):  66 (0x42)

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

dev/w1-eeprom.c

 /*
- * Eeprom support
- * Cesar Prados, 2013 GNU GPL2 or later
+ * Eeprom support (family 0x43)
+ * Cesar Prados, Alessandro Rubini, 2013. GNU GPL2 or later
  */
 #include <stdlib.h>
 #include <string.h>
@@ -11,39 +11,87 @@
 #define LSB_ADDR(X) ((X) & 0xFF)
 #define MSB_ADDR(X) (((X) & 0xFF00)>>8)
 
-int w1_write_eeprom(struct w1_dev *dev, int offset, const uint8_t *buffer,
-		    int blen)
+static int w1_write_page(struct w1_dev *dev, int offset, const uint8_t *buffer,
+			 int blen)
 {
-	int i;
-	int read_data;
+	int i, j, es;
 
+	/* First, write scratchpad */
 	w1_match_rom(dev);
 	w1_write_byte(dev->bus, W1_CMDR_W_SPAD);
-
 	w1_write_byte(dev->bus, LSB_ADDR(offset));
 	w1_write_byte(dev->bus, MSB_ADDR(offset));
-
-	for(i = 0; i < 32; i++)
+	for(i = 0; i < blen; i++)
 		w1_write_byte(dev->bus, buffer[i]);
 
+	/* Then, read it back, and remember the return E/S */
 	w1_match_rom(dev);
-	w1_write_byte(dev->bus, W1_CMDR_C_SPAD);
+	w1_write_byte(dev->bus, W1_CMDR_R_SPAD);
+	if (w1_read_byte(dev->bus) != LSB_ADDR(offset))
+		return -1;
+	if (w1_read_byte(dev->bus) != MSB_ADDR(offset))
+		return -2;
+	es = w1_read_byte(dev->bus);
+	for(i = 0; i < blen; i++) {
+		j = w1_read_byte(dev->bus);
+		if (j != buffer[i])
+			return -3;
+	}
 
+	/* Finally, "copy scratchpad" to actually write */
+	w1_match_rom(dev);
+	w1_write_byte(dev->bus, W1_CMDR_C_SPAD);
 	w1_write_byte(dev->bus, LSB_ADDR(offset));
 	w1_write_byte(dev->bus, MSB_ADDR(offset));
+	w1_write_byte(dev->bus, es);
+	usleep(10000); /* 10ms, in theory */
 
-	w1_write_byte(dev->bus, 0x1f);
-	usleep(10000);
+	/* Don't read back, as nothing useful is there (I get 0xf9, why?) */
+	return blen;
+}
 
-	read_data = w1_read_byte(dev->bus);
-	if (read_data != 0xaa)
-		return -1;
-	return 0;
+int w1_write_eeprom(struct w1_dev *dev, int offset, const uint8_t *buffer,
+		    int blen)
+{
+	int i, page, endpage;
+	int ret = 0;
+
+	/* Split the write into several page-local writes */
+	page = offset / 32;
+	endpage = (offset + blen - 1) / 32;
+
+	/* Traling part of first page */
+	if (offset % 32) {
+		if (endpage != page)
+			i = 32 - (offset % 32);
+		else
+			i = blen;
+		ret += w1_write_page(dev, offset, buffer, i);
+		if (ret < 0)
+			return ret;
+		buffer += i;
+		offset += i;
+		blen -= i;
+	}
+
+	/* Whole pages and leading part of last page */
+	while (blen > 0 ) {
+		i = blen;
+		if (blen > 32)
+			i = 32;
+		i = w1_write_page(dev, offset, buffer, i);
+		if (i < 0)
+			return i;
+		ret += i;
+		buffer += 32;
+		offset += 32;
+		blen -= 32;
+	}
+	return ret;
 }
 
 int w1_read_eeprom(struct w1_dev *dev, int offset, uint8_t *buffer, int blen)
 {
-
 	int i;
 
 	w1_match_rom(dev);
@@ -52,34 +100,63 @@ int w1_read_eeprom(struct w1_dev *dev, int offset, uint8_t *buffer, int blen)
 	w1_write_byte(dev->bus, LSB_ADDR(offset));
 	w1_write_byte(dev->bus, MSB_ADDR(offset));
 
-	for(i = 0; i < 32; i++)
+	/* There is no page-size limit in reading, just go on at will */
+	for(i = 0; i < blen; i++)
 		buffer[i] = w1_read_byte(dev->bus);
 
-	return 0;
+	return blen;
 }
 
 
-/* A shell command, for testing write*/
-static int cmd_w1_w(const char *args[])
+int w1_read_eeprom_bus(struct w1_bus *bus,
+			    int offset, uint8_t *buffer, int blen)
 {
-	struct w1_dev *d;
-	int page;
-	int blen;
-	char pn[32]="\0";
+	int i, class;
+
+	for (i = 0; i < W1_MAX_DEVICES; i++) {
+		class = w1_class(bus->devs + i);
+		if (class == 0x43)
+			return w1_read_eeprom(bus->devs + i, offset,
+					      buffer, blen);
+	}
+	/* not found */
+	return -1;
+}
 
-	d = wrpc_w1_bus.devs + 1;
+int w1_write_eeprom_bus(struct w1_bus *bus,
+			int offset, const uint8_t *buffer, int blen)
+{
+	int i, class;
 
-	pp_printf("Writing in device: %08x%08x\n",
-		  (int)(d->rom >> 32), (int)d->rom);
+	for (i = 0; i < W1_MAX_DEVICES; i++) {
+		class = w1_class(bus->devs + i);
+		if (class == 0x43)
+			return w1_write_eeprom(bus->devs + i, offset,
+					       buffer, blen);
+	}
+	/* not found */
+	return -1;
+}
 
-	page = atoi(args[0]);
+#define BLEN 32
 
-	blen = strlen(args[1]);
-	memcpy(pn, args[1], blen);
-	if(!w1_write_eeprom(d, page*0x20, (uint8_t *)pn, blen))
-		pp_printf("Write success\n");
+/* A shell command, for testing write: "w1w <offset> <byte> [<byte> ...]" */
+static int cmd_w1_w(const char *args[])
+{
+	int offset, i, blen;
+	unsigned char buf[BLEN];
 
-	return 0;
+	if (!args[0] || !args[1])
+		return -1;
+	offset = atoi(args[0]);
+	for (i = 1, blen = 0; args[i] && blen < BLEN; i++, blen++) {
+		buf[blen] = atoi(args[i]);
+		pp_printf("offset %4i (0x%03x): %3i (0x%02x)\n",
+			  offset + blen, offset + blen, buf[blen], buf[blen]);
+	}
+	i = w1_write_eeprom_bus(&wrpc_w1_bus, offset, buf, blen);
+	pp_printf("write(0x%x, %i): result = %i\n", offset, blen, i);
+	return i == blen ? 0 : -1;
 }
 
 DEFINE_WRC_COMMAND(w1w) = {
@@ -87,77 +164,29 @@ DEFINE_WRC_COMMAND(w1w) = {
 	.exec = cmd_w1_w,
 };
 
-/* A shell command, for testing read*/
+/* A shell command, for testing read: "w1w <offset> <len> */
 static int cmd_w1_r(const char *args[])
 {
-	struct w1_dev *d;
-	int page;
-	int i;
-	char pn[32]="\0";
-
-	d = wrpc_w1_bus.devs + 1;
-
-	pp_printf("Reading from device: %08x%08x\n",
-		  (int)(d->rom >> 32), (int)d->rom);
-
-	page = atoi(args[0]);
-
-	w1_read_eeprom(d, page*0x20, (uint8_t *)pn, 32);
+	int offset, i, blen;
+	unsigned char buf[BLEN];
 
-	for(i=0;i<32;i++)
-		pp_printf("%c",pn[i]);
-
-	pp_printf("\n");
-
-	return 0;
+	if (!args[0] || !args[1])
+		return -1;
+	offset = atoi(args[0]);
+	blen = atoi(args[1]);
+	if (blen > BLEN)
+		blen = BLEN;
+	i = w1_read_eeprom_bus(&wrpc_w1_bus, offset, buf, blen);
+	pp_printf("read(0x%x, %i): result = %i\n", offset, blen, i);
+	if (i <= 0 || i > blen) return -1;
+	for (blen = 0; blen < i; blen++) {
+		pp_printf("offset %4i (0x%03x): %3i (0x%02x)\n",
+			  offset + blen, offset + blen, buf[blen], buf[blen]);
+	}
+	return i == blen ? 0 : -1;
 }
 
-
-
 DEFINE_WRC_COMMAND(w1r) = {
 	.name = "w1r",
 	.exec = cmd_w1_r,
 };
-
-/* A shell command, for testing write/read*/
-static int cmd_w1_test(const char *args[])
-{
-	struct w1_dev *d;
-	int page;
-	int errors=0;
-	int blen;
-	int i;
-	char pn[32]="testing";
-
-	blen = strlen(pn);
-
-	d = wrpc_w1_bus.devs + 1;
-
-	pp_printf("Writing in device: %08x%08x\n",
-		  (int)(d->rom >> 32), (int)d->rom);
-
-	for(page = 0; page < 80; page++) {
-		if(!w1_write_eeprom(d, page * 0x20, (uint8_t *)pn, blen)) {
-			pp_printf("Page %i: success\n", page);
-		} else {
-			pp_printf("Page %i: error\n", page);
-			errors++;
-		}
-	}
-	pp_printf("Write Errors: %d \n", errors);
-
-	usleep(1000 * 1000);
-
-	for(page = 0; page < 80; page++) {
-		w1_read_eeprom(d, page * 0x20, (uint8_t *)pn, 32);
-		for(i = 0; i < 32; i++)
-			pp_printf("%c",pn[i]);
-		pp_printf("\n");
-	}
-	return 0;
-}
-
-DEFINE_WRC_COMMAND(w1test) = {
-	.name = "w1test",
-	.exec = cmd_w1_test,
-};