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rtc-ds1302: add some abstraction for new platform support

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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@misterjones.org>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Marc Zyngier 2010-05-24 14:33:47 -07:00 committed by Linus Torvalds
parent e17ab5cbed
commit 72cc8e51cf
1 changed files with 67 additions and 18 deletions
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85
drivers/rtc/rtc-ds1302.c
View file

@ -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);