Re: [rtc-linux] [PATCH] rtc: rp5c01 - Add NVRAM support

[Wan ZongShun]

Hi Geert ,

Minior comment below:

2010/6/13 Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>:
> 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@xxxxxxxxxxxxxx>
> --
> Question: Is a spinlock in priv the right kind of locking?
> Â Â Â Â ÂShould I use e.g. rtc-device.ops_lock instead?

Firstly, this 'Question' text should not put here, please put all
texts in front of '---'.
Secondly, You can not use rtc-device.ops_lock here, if so, it would
arouse dead lock,
before the ' rp5c01_read_time()' was called by RTC subsystem upper
API, rtc-device.ops_lock
has been required sucessfully, If continue to require the
rtc-device.ops_lock in ' rp5c01_read_time()',
the 'lock' will cannot be get, dead lock occurs.

>
> diff --git a/drivers/rtc/rtc-rp5c01.c b/drivers/rtc/rtc-rp5c01.c
> index a95f733..36eb661 100644
> --- a/drivers/rtc/rtc-rp5c01.c
> +++ b/drivers/rtc/rtc-rp5c01.c
> @@ -63,6 +63,8 @@ enum {
> Âstruct rp5c01_priv {
> Â Â Â Âu32 __iomem *regs;
> Â Â Â Âstruct rtc_device *rtc;
> + Â Â Â spinlock_t lock; Â Â Â Â/* against concurrent RTC/NVRAM access */
> + Â Â Â struct bin_attribute nvram_attr;
> Â};
>
> Âstatic 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)
> Â{
> Â Â Â Âstruct rp5c01_priv *priv = dev_get_drvdata(dev);
>
> + Â Â Â spin_lock_irq(&priv->lock);
> Â Â Â Ârp5c01_lock(priv);
>
> Â Â Â Âtm->tm_sec Â= rp5c01_read(priv, RP5C01_10_SECOND) * 10 +
> @@ -111,6 +114,7 @@ static int rp5c01_read_time(struct device *dev, struct rtc_time *tm)
> Â Â Â Â Â Â Â Âtm->tm_year += 100;
>
> Â Â Â Ârp5c01_unlock(priv);
> + Â Â Â spin_unlock_irq(&priv->lock);
>
> Â Â Â Âreturn rtc_valid_tm(tm);
> Â}
> @@ -119,6 +123,7 @@ static int rp5c01_set_time(struct device *dev, struct rtc_time *tm)
> Â{
> Â Â Â Âstruct rp5c01_priv *priv = dev_get_drvdata(dev);
>
> + Â Â Â spin_lock_irq(&priv->lock);
> Â Â Â Ârp5c01_lock(priv);
>
> Â Â Â Ârp5c01_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)
> Â Â Â Ârp5c01_write(priv, tm->tm_year % 10, RP5C01_1_YEAR);
>
> Â Â Â Ârp5c01_unlock(priv);
> + Â Â Â spin_unlock_irq(&priv->lock);
> Â Â Â Âreturn 0;
> Â}
>
> @@ -147,6 +153,72 @@ static const struct rtc_class_ops rp5c01_rtc_ops = {
>    Â.set_time    = rp5c01_set_time,
> Â};
>
> +
> +/*
> + * 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,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âstruct bin_attribute *bin_attr,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âchar *buf, loff_t pos, size_t size)
> +{
> + Â Â Â struct device *dev = container_of(kobj, struct device, kobj);
> + Â Â Â struct rp5c01_priv *priv = dev_get_drvdata(dev);
> + Â Â Â ssize_t count;
> +
> + Â Â Â spin_lock_irq(&priv->lock);
> +
> + Â Â Â for (count = 0; size > 0 && pos < RP5C01_MODE; count++, size--) {
> + Â Â Â Â Â Â Â u8 data;
> +
> + Â Â Â Â Â Â Â rp5c01_write(priv,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK10,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE);
> + Â Â Â Â Â Â Â data = rp5c01_read(priv, pos) << 4;
> + Â Â Â Â Â Â Â rp5c01_write(priv,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK11,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE);
> + Â Â Â Â Â Â Â data |= rp5c01_read(priv, pos++);
> + Â Â Â Â Â Â Â rp5c01_write(priv, RP5C01_MODE_TIMER_EN | RP5C01_MODE_MODE01,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE);
> + Â Â Â Â Â Â Â *buf++ = data;
> + Â Â Â }
> +
> + Â Â Â spin_unlock_irq(&priv->lock);
> + Â Â Â return count;
> +}
> +
> +static ssize_t rp5c01_nvram_write(struct file *filp, struct kobject *kobj,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â struct bin_attribute *bin_attr,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â char *buf, loff_t pos, size_t size)
> +{
> + Â Â Â struct device *dev = container_of(kobj, struct device, kobj);
> + Â Â Â struct rp5c01_priv *priv = dev_get_drvdata(dev);
> + Â Â Â ssize_t count;
> +
> + Â Â Â spin_lock_irq(&priv->lock);
> +
> + Â Â Â for (count = 0; size > 0 && pos < RP5C01_MODE; count++, size--) {
> + Â Â Â Â Â Â Â u8 data = *buf++;
> +
> + Â Â Â Â Â Â Â rp5c01_write(priv,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK10,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE);
> + Â Â Â Â Â Â Â rp5c01_write(priv, data >> 4, pos);
> + Â Â Â Â Â Â Â rp5c01_write(priv,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK11,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE);
> + Â Â Â Â Â Â Â rp5c01_write(priv, data & 0xf, pos++);
> + Â Â Â Â Â Â Â rp5c01_write(priv, RP5C01_MODE_TIMER_EN | RP5C01_MODE_MODE01,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â ÂRP5C01_MODE);
> + Â Â Â }
> +
> + Â Â Â spin_unlock_irq(&priv->lock);
> + Â Â Â return count;
> +}
> +
> Âstatic int __init rp5c01_rtc_probe(struct platform_device *dev)
> Â{
> Â Â Â Âstruct resource *res;
> @@ -168,6 +240,15 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev)
> Â Â Â Â Â Â Â Âgoto out_free_priv;
> Â Â Â Â}
>
> + Â Â Â sysfs_bin_attr_init(&priv->nvram_attr);
> + Â Â Â priv->nvram_attr.attr.name = "nvram";
> + Â Â Â priv->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
> + Â Â Â priv->nvram_attr.read = rp5c01_nvram_read;
> + Â Â Â priv->nvram_attr.write = rp5c01_nvram_write;
> + Â Â Â priv->nvram_attr.size = RP5C01_MODE;
> +
> + Â Â Â spin_lock_init(&priv->lock);
> +
> Â Â Â Ârtc = rtc_device_register("rtc-rp5c01", &dev->dev, &rp5c01_rtc_ops,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â ÂTHIS_MODULE);
> Â Â Â Âif (IS_ERR(rtc)) {
> @@ -177,8 +258,15 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev)
>
> Â Â Â Âpriv->rtc = rtc;
> Â Â Â Âplatform_set_drvdata(dev, priv);
> +
> + Â Â Â error = sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr);
> + Â Â Â if (error)
> + Â Â Â Â Â Â Â goto out_unregister;
> +
> Â Â Â Âreturn 0;
>
> +out_unregister:
> + Â Â Â rtc_device_unregister(rtc);
> Âout_unmap:
> Â Â Â Âiounmap(priv->regs);
> Âout_free_priv:
> @@ -190,6 +278,7 @@ static int __exit rp5c01_rtc_remove(struct platform_device *dev)
> Â{
> Â Â Â Âstruct rp5c01_priv *priv = platform_get_drvdata(dev);
>
> + Â Â Â sysfs_remove_bin_file(&dev->dev.kobj, &priv->nvram_attr);
> Â Â Â Ârtc_device_unregister(priv->rtc);
> Â Â Â Âiounmap(priv->regs);
> Â Â Â Âkfree(priv);
> --
> 1.7.0.4
>
> Gr{oetje,eeting}s,
>
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â ÂGeert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â-- Linus Torvalds
>
> --
> You received this message because you are subscribed to "rtc-linux".
> Membership options at http://groups.google.com/group/rtc-linux .
> Please read http://groups.google.com/group/rtc-linux/web/checklist
> before submitting a driver.



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