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From: Marc Zyngier on 11 Apr 2010 18:00
The current ds1302 driver (or at least the one that lives in /drivers/rtc)
seems to be designed for memory mapped devices only. This make it quite
hard to add support for GPIO-based implementations (as this is the case
for the upcoming Arcom Vulcan).

This patch moves the direct register access to inline functions with
explicit names. Still not as good as a proper platform driver, but at
least neater.

Signed-off-by: Marc Zyngier <maz(a)misterjones.org>
Cc: Paul Gortmaker <p_gortmaker(a)yahoo.com>
Cc: Alessandro Zummo <a.zummo(a)towertech.it>
Cc: Paul Mundt <lethal(a)linux-sh.org>
---
drivers/rtc/rtc-ds1302.c | 85 ++++++++++++++++++++++++++++++++++++----------
1 files changed, 67 insertions(+), 18 deletions(-)

diff --git a/drivers/rtc/rtc-ds1302.c b/drivers/rtc/rtc-ds1302.c
index 532acf9..359d1e0 100644
--- a/drivers/rtc/rtc-ds1302.c
+++ b/drivers/rtc/rtc-ds1302.c
@@ -16,7 +16,6 @@
#include <linux/rtc.h>
#include <linux/io.h>
#include <linux/bcd.h>
-#include <asm/rtc.h>

#define DRV_NAME "rtc-ds1302"
#define DRV_VERSION "0.1.1"
@@ -34,14 +33,55 @@
#define RTC_ADDR_MIN 0x01 /* Address of minute register */
#define RTC_ADDR_SEC 0x00 /* Address of second register */

+#ifdef CONFIG_SH_SECUREEDGE5410
+#include <asm/rtc.h>
+#include <mach/snapgear.h>
+
#define RTC_RESET 0x1000
#define RTC_IODATA 0x0800
#define RTC_SCLK 0x0400

-#ifdef CONFIG_SH_SECUREEDGE5410
-#include <mach/snapgear.h>
#define set_dp(x) SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
#define get_dp() SECUREEDGE_READ_IOPORT()
+#define ds1302_set_tx()
+#define ds1302_set_rx()
+
+static inline int ds1302_hw_init(void)
+{
+ return 0;
+}
+
+static inline void ds1302_reset(void)
+{
+ set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+}
+
+static inline void ds1302_clock(void)
+{
+ set_dp(get_dp() | RTC_SCLK); /* clock high */
+ set_dp(get_dp() & ~RTC_SCLK); /* clock low */
+}
+
+static inline void ds1302_start(void)
+{
+ set_dp(get_dp() | RTC_RESET);
+}
+
+static inline void ds1302_stop(void)
+{
+ set_dp(get_dp() & ~RTC_RESET);
+}
+
+static inline void ds1302_txbit(int bit)
+{
+ set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
+}
+
+static inline int ds1302_rxbit(void)
+{
+ return !!(get_dp() & RTC_IODATA);
+}
+
#else
#error "Add support for your platform"
#endif
@@ -50,11 +90,11 @@ static void ds1302_sendbits(unsigned int val)
{
int i;

+ ds1302_set_tx();
+
for (i = 8; (i); i--, val >>= 1) {
- set_dp((get_dp() & ~RTC_IODATA) | ((val & 0x1) ?
- RTC_IODATA : 0));
- set_dp(get_dp() | RTC_SCLK); /* clock high */
- set_dp(get_dp() & ~RTC_SCLK); /* clock low */
+ ds1302_txbit(val & 0x1);
+ ds1302_clock();
}
}

@@ -63,10 +103,11 @@ static unsigned int ds1302_recvbits(void)
unsigned int val;
int i;

+ ds1302_set_rx();
+
for (i = 0, val = 0; (i < 8); i++) {
- val |= (((get_dp() & RTC_IODATA) ? 1 : 0) << i);
- set_dp(get_dp() | RTC_SCLK); /* clock high */
- set_dp(get_dp() & ~RTC_SCLK); /* clock low */
+ val |= (ds1302_rxbit() << i);
+ ds1302_clock();
}

return val;
@@ -76,23 +117,24 @@ static unsigned int ds1302_readbyte(unsigned int addr)
{
unsigned int val;

- set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+ ds1302_reset();

- set_dp(get_dp() | RTC_RESET);
+ ds1302_start();
ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
val = ds1302_recvbits();
- set_dp(get_dp() & ~RTC_RESET);
+ ds1302_stop();

return val;
}

static void ds1302_writebyte(unsigned int addr, unsigned int val)
{
- set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
- set_dp(get_dp() | RTC_RESET);
+ ds1302_reset();
+
+ ds1302_start();
ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
ds1302_sendbits(val);
- set_dp(get_dp() & ~RTC_RESET);
+ ds1302_stop();
}

static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
@@ -167,13 +209,20 @@ static int __init ds1302_rtc_probe(struct platform_device *pdev)
{
struct rtc_device *rtc;

+ if (ds1302_hw_init()) {
+ dev_err(&pdev->dev, "Failed to init communication channel");
+ return -EINVAL;
+ }
+
/* Reset */
- set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+ ds1302_reset();

/* Write a magic value to the DS1302 RAM, and see if it sticks. */
ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
- if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42)
+ if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
+ dev_err(&pdev->dev, "Failed to probe");
return -ENODEV;
+ }

rtc = rtc_device_register("ds1302", &pdev->dev,
&ds1302_rtc_ops, THIS_MODULE);
--
1.7.0.4

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