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rtc: rp5c01: add NVRAM support
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The Ricoh RP5C01 RTC contains 26 x 4 bits of NVRAM.  Provide access to it
via a sysfs "nvram" attribute file.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Geert Uytterhoeven authored and Linus Torvalds committed Aug 11, 2010
1 parent de639c3 commit 22e3d63
Showing 1 changed file with 89 additions and 0 deletions.
89 changes: 89 additions & 0 deletions drivers/rtc/rtc-rp5c01.c
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,8 @@ enum {
struct rp5c01_priv {
u32 __iomem *regs;
struct rtc_device *rtc;
spinlock_t lock; /* against concurrent RTC/NVRAM access */
struct bin_attribute nvram_attr;
};

static inline unsigned int rp5c01_read(struct rp5c01_priv *priv,
Expand Down Expand Up @@ -92,6 +94,7 @@ static int rp5c01_read_time(struct device *dev, struct rtc_time *tm)
{
struct rp5c01_priv *priv = dev_get_drvdata(dev);

spin_lock_irq(&priv->lock);
rp5c01_lock(priv);

tm->tm_sec = rp5c01_read(priv, RP5C01_10_SECOND) * 10 +
Expand All @@ -111,6 +114,7 @@ static int rp5c01_read_time(struct device *dev, struct rtc_time *tm)
tm->tm_year += 100;

rp5c01_unlock(priv);
spin_unlock_irq(&priv->lock);

return rtc_valid_tm(tm);
}
Expand All @@ -119,6 +123,7 @@ static int rp5c01_set_time(struct device *dev, struct rtc_time *tm)
{
struct rp5c01_priv *priv = dev_get_drvdata(dev);

spin_lock_irq(&priv->lock);
rp5c01_lock(priv);

rp5c01_write(priv, tm->tm_sec / 10, RP5C01_10_SECOND);
Expand All @@ -139,6 +144,7 @@ static int rp5c01_set_time(struct device *dev, struct rtc_time *tm)
rp5c01_write(priv, tm->tm_year % 10, RP5C01_1_YEAR);

rp5c01_unlock(priv);
spin_unlock_irq(&priv->lock);
return 0;
}

Expand All @@ -147,6 +153,72 @@ static const struct rtc_class_ops rp5c01_rtc_ops = {
.set_time = rp5c01_set_time,
};


/*
* The NVRAM is organized as 2 blocks of 13 nibbles of 4 bits.
* We provide access to them like AmigaOS does: the high nibble of each 8-bit
* byte is stored in BLOCK10, the low nibble in BLOCK11.
*/

static ssize_t rp5c01_nvram_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t pos, size_t size)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct rp5c01_priv *priv = dev_get_drvdata(dev);
ssize_t count;

spin_lock_irq(&priv->lock);

for (count = 0; size > 0 && pos < RP5C01_MODE; count++, size--) {
u8 data;

rp5c01_write(priv,
RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK10,
RP5C01_MODE);
data = rp5c01_read(priv, pos) << 4;
rp5c01_write(priv,
RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK11,
RP5C01_MODE);
data |= rp5c01_read(priv, pos++);
rp5c01_write(priv, RP5C01_MODE_TIMER_EN | RP5C01_MODE_MODE01,
RP5C01_MODE);
*buf++ = data;
}

spin_unlock_irq(&priv->lock);
return count;
}

static ssize_t rp5c01_nvram_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t pos, size_t size)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct rp5c01_priv *priv = dev_get_drvdata(dev);
ssize_t count;

spin_lock_irq(&priv->lock);

for (count = 0; size > 0 && pos < RP5C01_MODE; count++, size--) {
u8 data = *buf++;

rp5c01_write(priv,
RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK10,
RP5C01_MODE);
rp5c01_write(priv, data >> 4, pos);
rp5c01_write(priv,
RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK11,
RP5C01_MODE);
rp5c01_write(priv, data & 0xf, pos++);
rp5c01_write(priv, RP5C01_MODE_TIMER_EN | RP5C01_MODE_MODE01,
RP5C01_MODE);
}

spin_unlock_irq(&priv->lock);
return count;
}

static int __init rp5c01_rtc_probe(struct platform_device *dev)
{
struct resource *res;
Expand All @@ -168,6 +240,15 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev)
goto out_free_priv;
}

sysfs_bin_attr_init(&priv->nvram_attr);
priv->nvram_attr.attr.name = "nvram";
priv->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
priv->nvram_attr.read = rp5c01_nvram_read;
priv->nvram_attr.write = rp5c01_nvram_write;
priv->nvram_attr.size = RP5C01_MODE;

spin_lock_init(&priv->lock);

rtc = rtc_device_register("rtc-rp5c01", &dev->dev, &rp5c01_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc)) {
Expand All @@ -177,8 +258,15 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev)

priv->rtc = rtc;
platform_set_drvdata(dev, priv);

error = sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr);
if (error)
goto out_unregister;

return 0;

out_unregister:
rtc_device_unregister(rtc);
out_unmap:
iounmap(priv->regs);
out_free_priv:
Expand All @@ -190,6 +278,7 @@ static int __exit rp5c01_rtc_remove(struct platform_device *dev)
{
struct rp5c01_priv *priv = platform_get_drvdata(dev);

sysfs_remove_bin_file(&dev->dev.kobj, &priv->nvram_attr);
rtc_device_unregister(priv->rtc);
iounmap(priv->regs);
kfree(priv);
Expand Down

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