[PATCH] rtc: ds1307: generalise ram size and offset

[Austin Boyle]

From: Austin Boyle <Austin.Boyle@xxxxxxxxxxxx>

This patch generalises NVRAM to support RAM with other size and offset, such
as the 64 bytes of SRAM on the MCP7941x.

Cc: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
Cc: David Anderson <danders.dev@xxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
Signed-off-by: Austin Boyle <Austin.Boyle@xxxxxxxxxxxx>
---
this patch is based on Wolfram Sang's tree:
git://git.pengutronix.de/git/wsa/linux-2.6.git ds1307

patch depends on:
rtc: ds1307: comment and format cleanup 21af5f7bd6
rtc: ds1307: simplify irq setup code  8c63e03627
rtc: ds1307: refactor chip_desc table e246db081d
rtc: add initial support for mcp7941x parts e69bba2d3a

--- a/drivers/rtc/rtc-ds1307.c	2011-10-10 11:22:22.674690998 +1300
+++ b/drivers/rtc/rtc-ds1307.c	2011-11-03 09:13:06.662159569 +1300
@@ -104,10 +104,12 @@ enum ds_type {
 
 struct ds1307 {
 	u8			offset; /* register's offset */
+	u16			ram_offset;
+	u16			ram_size;
 	u8			regs[11];
 	enum ds_type		type;
 	unsigned long		flags;
-#define HAS_NVRAM	0		/* bit 0 == sysfs file active */
+#define HAS_RAM	0			/* bit 0 == sysfs file active */
 #define HAS_ALARM	1		/* bit 1 == irq claimed */
 	struct i2c_client	*client;
 	struct rtc_device	*rtc;
@@ -119,19 +121,19 @@ struct ds1307 {
 };
 
 struct chip_desc {
-	unsigned		nvram56:1;
+	unsigned		ram:1;
 	unsigned		alarm:1;
 };
 
 static const struct chip_desc chips[last_ds_type] = {
 	[ds_1307] = {
-		.nvram56	= 1,
+		.ram		= 1,
 	},
 	[ds_1337] = {
 		.alarm		= 1,
 	},
 	[ds_1338] = {
-		.nvram56	= 1,
+		.ram		= 1,
 	},
 	[ds_1339] = {
 		.alarm		= 1,
@@ -139,6 +141,9 @@ static const struct chip_desc chips[last
 	[ds_3231] = {
 		.alarm		= 1,
 	},
+	[mcp7941x] = {
+		.ram		= 1,
+	},
 };
 
 static const struct i2c_device_id ds1307_id[] = {
@@ -543,10 +548,8 @@ static const struct rtc_class_ops ds13xx
 
 /*----------------------------------------------------------------------*/
 
-#define NVRAM_SIZE	56
-
 static ssize_t
-ds1307_nvram_read(struct file *filp, struct kobject *kobj,
+ds1307_ram_read(struct file *filp, struct kobject *kobj,
 		struct bin_attribute *attr,
 		char *buf, loff_t off, size_t count)
 {
@@ -557,21 +560,22 @@ ds1307_nvram_read(struct file *filp, str
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= NVRAM_SIZE))
+	if (unlikely(off >= ds1307->ram_size))
 		return 0;
-	if ((off + count) > NVRAM_SIZE)
-		count = NVRAM_SIZE - off;
+	if ((off + count) > ds1307->ram_size)
+		count = ds1307->ram_size - off;
 	if (unlikely(!count))
 		return count;
 
-	result = ds1307->read_block_data(client, 8 + off, count, buf);
+	result = ds1307->read_block_data(client, ds1307->ram_offset + off,
+								count, buf);
 	if (result < 0)
-		dev_err(&client->dev, "%s error %d\n", "nvram read", result);
+		dev_err(&client->dev, "%s error %d\n", "ram read", result);
 	return result;
 }
 
 static ssize_t
-ds1307_nvram_write(struct file *filp, struct kobject *kobj,
+ds1307_ram_write(struct file *filp, struct kobject *kobj,
 		struct bin_attribute *attr,
 		char *buf, loff_t off, size_t count)
 {
@@ -582,30 +586,30 @@ ds1307_nvram_write(struct file *filp, st
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= NVRAM_SIZE))
+	if (unlikely(off >= ds1307->ram_size))
 		return -EFBIG;
-	if ((off + count) > NVRAM_SIZE)
-		count = NVRAM_SIZE - off;
+	if ((off + count) > ds1307->ram_size)
+		count = ds1307->ram_size - off;
 	if (unlikely(!count))
 		return count;
 
-	result = ds1307->write_block_data(client, 8 + off, count, buf);
+	result = ds1307->write_block_data(client, ds1307->ram_offset + off,
+								count, buf);
 	if (result < 0) {
-		dev_err(&client->dev, "%s error %d\n", "nvram write", result);
+		dev_err(&client->dev, "%s error %d\n", "ram write", result);
 		return result;
 	}
 	return count;
 }
 
-static struct bin_attribute nvram = {
+static struct bin_attribute ram = {
 	.attr = {
-		.name	= "nvram",
+		.name	= "ram",
 		.mode	= S_IRUGO | S_IWUSR,
 	},
 
-	.read	= ds1307_nvram_read,
-	.write	= ds1307_nvram_write,
-	.size	= NVRAM_SIZE,
+	.read	= ds1307_ram_read,
+	.write	= ds1307_ram_write,
 };
 
 /*----------------------------------------------------------------------*/
@@ -692,6 +696,9 @@ static int __devinit ds1307_probe(struct
 		break;
 
 	case rx_8025:
+		ds1307->ram_size = 64; /* 64 bytes SRAM */
+		ds1307->ram_offset = 0x20;
+
 		tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 				RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 		if (tmp != 2) {
@@ -758,6 +765,8 @@ static int __devinit ds1307_probe(struct
 		break;
 	case ds_1388:
 		ds1307->offset = 1; /* Seconds starts at 1 */
+		ds1307->ram_size = 56; /* 56 bytes NVRAM */
+		ds1307->ram_offset = 8;
 		break;
 	default:
 		break;
@@ -893,11 +902,12 @@ read_rtc:
 		dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 	}
 
-	if (chip && chip->nvram56) {
-		err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
+	if (chip && chip->ram) {
+		ram.size = ds1307->ram_size;
+		err = sysfs_create_bin_file(&client->dev.kobj, &ram);
 		if (err == 0) {
-			set_bit(HAS_NVRAM, &ds1307->flags);
-			dev_info(&client->dev, "56 bytes nvram\n");
+			set_bit(HAS_RAM, &ds1307->flags);
+			dev_info(&client->dev, "%zd bytes ram\n", ram.size);
 		}
 	}
 
@@ -919,8 +929,8 @@ static int __devexit ds1307_remove(struc
 		cancel_work_sync(&ds1307->work);
 	}
 
-	if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
-		sysfs_remove_bin_file(&client->dev.kobj, &nvram);
+	if (test_and_clear_bit(HAS_RAM, &ds1307->flags))
+		sysfs_remove_bin_file(&client->dev.kobj, &ram);
 
 	rtc_device_unregister(ds1307->rtc);
 	kfree(ds1307);


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