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Message-ID: <48B40B68.1040607@harris.com>
Date: Tue, 26 Aug 2008 09:55:52 -0400
From: "Steven A. Falco" <sfalco@...ris.com>
To: Will Newton <will.newton@...il.com>
CC: linux-kernel@...r.kernel.org
Subject: Re: [RFC] Driver for Real Time Clock chip ST M41T65
Will Newton wrote:
> On Mon, Aug 25, 2008 at 6:27 PM, Steven A. Falco <sfalco@...ris.com> wrote:
>> I will be using a Real Time Clock chip, ST M41T65, on a new embedded system.
>> The chip is quite similar to the M41T8x family, which already has driver
>> rtc-m41t80.c.
>>
>> Would it be more acceptible to generalize rtc-m41t80.c (perhaps renaming it to
>> rtc-m41txx.c) or would it be better to create a new rtc-m41t6x.c?
Thanks for the feedback. Here is a respin which addresses your comments.
I'd also like to know if I should submit a new driver or mod the existing
one. If I mod the existing one, should it be renamed, should I update the
Kconfig, existing defconfigs, etc?
Signed-off-by: Steven A. Falco <sfalco@...ris.com>
diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index a3e0880..7eb4e05 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -55,21 +55,27 @@
#define M41T80_ALHOUR_HT (1 << 6) /* HT: Halt Update Bit */
#define M41T80_FLAGS_AF (1 << 6) /* AF: Alarm Flag Bit */
#define M41T80_FLAGS_BATT_LOW (1 << 4) /* BL: Battery Low Bit */
+#define M41T80_WATCHDOG_RB2 (1 << 7) /* RB: Watchdog resolution */
+#define M41T80_WATCHDOG_RB1 (1 << 1) /* RB: Watchdog resolution */
+#define M41T80_WATCHDOG_RB0 (1 << 0) /* RB: Watchdog resolution */
-#define M41T80_FEATURE_HT (1 << 0)
-#define M41T80_FEATURE_BL (1 << 1)
+#define M41T80_FEATURE_HT (1 << 0) /* Halt feature */
+#define M41T80_FEATURE_BL (1 << 1) /* Battery low indicator */
+#define M41T80_FEATURE_SQ (1 << 2) /* Squarewave feature */
+#define M41T80_FEATURE_WD (1 << 3) /* Extra watchdog resolution */
#define DRV_VERSION "0.05"
static const struct i2c_device_id m41t80_id[] = {
- { "m41t80", 0 },
- { "m41t81", M41T80_FEATURE_HT },
- { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL },
- { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL },
- { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL },
- { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL },
- { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL },
- { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL },
+ { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
+ { "m41t80", M41T80_FEATURE_SQ },
+ { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
+ { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+ { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+ { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+ { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+ { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+ { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
{ }
};
MODULE_DEVICE_TABLE(i2c, m41t80_id);
@@ -385,8 +391,12 @@ static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
+ struct m41t80_data *clientdata = i2c_get_clientdata(client);
int val;
+ if (!(clientdata->features & M41T80_FEATURE_SQ))
+ return -EINVAL;
+
val = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
if (val < 0)
return -EIO;
@@ -407,9 +417,13 @@ static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
const char *buf, size_t count)
{
struct i2c_client *client = to_i2c_client(dev);
+ struct m41t80_data *clientdata = i2c_get_clientdata(client);
int almon, sqw;
int val = simple_strtoul(buf, NULL, 0);
+ if (!(clientdata->features & M41T80_FEATURE_SQ))
+ return -EINVAL;
+
if (val) {
if (!is_power_of_2(val))
return -EINVAL;
@@ -498,6 +512,8 @@ static void wdt_ping(void)
.buf = i2c_data,
},
};
+ struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
+
i2c_data[0] = 0x09; /* watchdog register */
if (wdt_margin > 31)
@@ -508,6 +524,13 @@ static void wdt_ping(void)
*/
i2c_data[1] = wdt_margin<<2 | 0x82;
+ /*
+ * M41T65 has three bits for watchdog resolution. Don't set bit 7, as
+ * that would be an invalid resolution.
+ */
+ if (clientdata->features & M41T80_FEATURE_WD)
+ i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
+
i2c_transfer(save_client->adapter, msgs1, 1);
}
--
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