On 29/07/2019 20:45:57+0200, Thomas Bogendoerfer wrote:

On Thu, 25 Jul 2019 12:47:16 +0100
Lee Jones [off-list ref] wrote:

quoted

On Thu, 13 Jun 2019, Thomas Bogendoerfer wrote:

quoted

+/*
+ * On IP30 the RTC (a DS1687) is behind the IOC3 on the generic
+ * ByteBus regions. We have to write the RTC address of interest to
+ * IOC3_BYTEBUS_DEV1, then read the data from IOC3_BYTEBUS_DEV2.
+ * rtc->regs already points to IOC3_BYTEBUS_DEV1.
+ */
+#define IP30_RTC_ADDR(rtc) (rtc->regs)
+#define IP30_RTC_DATA(rtc) ((rtc->regs) + IOC3_BYTEBUS_DEV2 - IOC3_BYTEBUS_DEV1)
+
+static u8 ip30_rtc_read(struct ds1685_priv *rtc, int reg)
+{
+	writeb((reg & 0x7f), IP30_RTC_ADDR(rtc));
+	return readb(IP30_RTC_DATA(rtc));
+}
+
+static void ip30_rtc_write(struct ds1685_priv *rtc, int reg, u8 value)
+{
+	writeb((reg & 0x7f), IP30_RTC_ADDR(rtc));
+	writeb(value, IP30_RTC_DATA(rtc));
+}

Why is this not in the RTC driver?

because rtc1685 is used in different systems and accessing the chip
differs between those systems. 

quoted

quoted

+static struct ds1685_rtc_platform_data ip30_rtc_platform_data = {
+	.bcd_mode = false,
+	.no_irq = false,
+	.uie_unsupported = true,
+	.alloc_io_resources = true,

quoted

+	.plat_read = ip30_rtc_read,
+	.plat_write = ip30_rtc_write,

Call-backs in a non-subsystem API is pretty ugly IMHO.

I agree

quoted

Where are these called from?

drivers/rtc/rtc-ds1685.c

I could do the same as done for serial8250 and add an additional .c file
in  drivers/rtc which handles this for SGI-IP30. Alexandre would this work
for you as well ?

As it is not particularly big, you could put that directly in
rtc-ds1685.c.


-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com