rtc: rp5c01: add NVRAM support

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>

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-rp5c01.c b/drivers/rtc/rtc-rp5c01.c
index a95f733bb15a..36eb66184461 100644
--- a/drivers/rtc/rtc-rp5c01.c
+++ b/drivers/rtc/rtc-rp5c01.c
@@ -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,
@@ -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 +
@@ -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);
 }
@@ -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);
@@ -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;
 }
 
@@ -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;
@@ -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)) {
@@ -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:
@@ -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);