From: Brad Campbell <brad@fnarfbargle.com>
To: Henrik Rydberg <rydberg@bitmath.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-hwmon@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
hns@goldelico.com, Guenter Roeck <linux@roeck-us.net>,
Andreas Kemnade <andreas@kemnade.info>,
Jean Delvare <jdelvare@suse.com>
Subject: [PATCH v3] applesmc: Re-work SMC comms
Date: Sun, 8 Nov 2020 12:00:03 +1100 [thread overview]
Message-ID: <57057d07-d3a0-8713-8365-7b12ca222bae@fnarfbargle.com> (raw)
In-Reply-To: <5310c0ab-0f80-1f9e-8807-066223edae13@bitmath.org>
G'day Henrik,
I noticed you'd also loosened up the requirement for SMC_STATUS_BUSY in read_smc(). I assume
that causes problems on the early Macbook. This is revised on the one sent earlier.
If you could test this on your Air1,1 it'd be appreciated.
Commit fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") introduced
an issue whereby communication with the SMC became unreliable with write
errors like :
[ 120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40
[ 120.378621] applesmc: LKSB: write data fail
[ 120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40
[ 120.512787] applesmc: LKSB: write data fail
The original code appeared to be timing sensitive and was not reliable with
the timing changes in the aforementioned commit.
This patch re-factors the SMC communication to remove the timing
dependencies and restore function with the changes previously committed.
Tested on : MacbookAir6,2 MacBookPro11,1 iMac12,2
Fixes: fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()")
Reported-by: Andreas Kemnade <andreas@kemnade.info>
Tested-by: Andreas Kemnade <andreas@kemnade.info> # MacBookAir6,2
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Brad Campbell <brad@fnarfbargle.com>
Signed-off-by: Henrik Rydberg <rydberg@bitmath.org>
---
Changelog :
v1 : Inital attempt
v2 : Address logic and coding style
v3 : Removed some debug hangover. Added tested-by. Modifications for MacBookAir1,1
diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index a18887990f4a..3e968abb37aa 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -32,6 +32,7 @@
#include <linux/hwmon.h>
#include <linux/workqueue.h>
#include <linux/err.h>
+#include <linux/bits.h>
/* data port used by Apple SMC */
#define APPLESMC_DATA_PORT 0x300
@@ -42,6 +43,11 @@
#define APPLESMC_MAX_DATA_LENGTH 32
+/* Apple SMC status bits */
+#define SMC_STATUS_AWAITING_DATA BIT(0) /* SMC has data waiting */
+#define SMC_STATUS_IB_CLOSED BIT(1) /* Will ignore any input */
+#define SMC_STATUS_BUSY BIT(2) /* Command in progress */
+
/* wait up to 128 ms for a status change. */
#define APPLESMC_MIN_WAIT 0x0010
#define APPLESMC_RETRY_WAIT 0x0100
@@ -151,65 +157,73 @@ static unsigned int key_at_index;
static struct workqueue_struct *applesmc_led_wq;
/*
- * wait_read - Wait for a byte to appear on SMC port. Callers must
- * hold applesmc_lock.
+ * Wait for specific status bits with a mask on the SMC
+ * Used before and after writes, and before reads
*/
-static int wait_read(void)
+
+static int wait_status(u8 val, u8 mask)
{
unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC;
u8 status;
int us;
+ udelay(APPLESMC_MIN_WAIT);
for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
- usleep_range(us, us * 16);
status = inb(APPLESMC_CMD_PORT);
- /* read: wait for smc to settle */
- if (status & 0x01)
+ if ((status & mask) == val)
return 0;
/* timeout: give up */
if (time_after(jiffies, end))
break;
+ usleep_range(us, us * 16);
}
-
- pr_warn("wait_read() fail: 0x%02x\n", status);
return -EIO;
}
/*
- * send_byte - Write to SMC port, retrying when necessary. Callers
+ * send_byte_data - Write to SMC data port. Callers
* must hold applesmc_lock.
+ * Parameter skip must be true on the last write of any
+ * command or it'll time out.
*/
-static int send_byte(u8 cmd, u16 port)
+
+static int send_byte_data(u8 cmd, u16 port, bool skip)
{
- u8 status;
- int us;
- unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC;
+ int ret;
+ ret = wait_status(SMC_STATUS_BUSY, SMC_STATUS_BUSY | SMC_STATUS_IB_CLOSED);
+ if (ret)
+ return ret;
outb(cmd, port);
- for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
- usleep_range(us, us * 16);
- status = inb(APPLESMC_CMD_PORT);
- /* write: wait for smc to settle */
- if (status & 0x02)
- continue;
- /* ready: cmd accepted, return */
- if (status & 0x04)
- return 0;
- /* timeout: give up */
- if (time_after(jiffies, end))
- break;
- /* busy: long wait and resend */
- udelay(APPLESMC_RETRY_WAIT);
- outb(cmd, port);
- }
+ return wait_status(skip ? 0 : SMC_STATUS_BUSY, SMC_STATUS_BUSY);
+}
- pr_warn("send_byte(0x%02x, 0x%04x) fail: 0x%02x\n", cmd, port, status);
- return -EIO;
+static int send_byte(u8 cmd, u16 port)
+{
+ return send_byte_data(cmd, port, false);
}
+/*
+ * send_command - Write a command to the SMC. Callers must hold applesmc_lock.
+ * If SMC is in undefined state, any new command write resets the state machine.
+ */
+
static int send_command(u8 cmd)
{
- return send_byte(cmd, APPLESMC_CMD_PORT);
+ int ret;
+ int i;
+
+ for (i = 0; i < 16; i++) {
+ ret = wait_status(0, SMC_STATUS_IB_CLOSED);
+ if (ret)
+ return ret;
+
+ outb(cmd, APPLESMC_CMD_PORT);
+ ret = wait_status(SMC_STATUS_BUSY, SMC_STATUS_BUSY);
+ if (!ret)
+ return ret;
+ }
+ return -EIO;
}
static int send_argument(const char *key)
@@ -239,7 +253,8 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len)
}
for (i = 0; i < len; i++) {
- if (wait_read()) {
+ if (wait_status(SMC_STATUS_AWAITING_DATA,
+ SMC_STATUS_AWAITING_DATA | SMC_STATUS_IB_CLOSED)) {
pr_warn("%.4s: read data[%d] fail\n", key, i);
return -EIO;
}
@@ -250,7 +265,7 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len)
for (i = 0; i < 16; i++) {
udelay(APPLESMC_MIN_WAIT);
status = inb(APPLESMC_CMD_PORT);
- if (!(status & 0x01))
+ if (!(status & SMC_STATUS_AWAITING_DATA))
break;
data = inb(APPLESMC_DATA_PORT);
}
@@ -275,7 +290,7 @@ static int write_smc(u8 cmd, const char *key, const u8 *buffer, u8 len)
}
for (i = 0; i < len; i++) {
- if (send_byte(buffer[i], APPLESMC_DATA_PORT)) {
+ if (send_byte_data(buffer[i], APPLESMC_DATA_PORT, i == len - 1)) {
pr_warn("%s: write data fail\n", key);
return -EIO;
}
next prev parent reply other threads:[~2020-11-08 1:00 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 8:54 [REGRESSION] hwmon: (applesmc) avoid overlong udelay() Andreas Kemnade
2020-09-30 16:44 ` Guenter Roeck
2020-09-30 20:00 ` Arnd Bergmann
2020-10-01 22:22 ` Andreas Kemnade
2020-10-02 4:07 ` Guenter Roeck
2020-10-06 7:02 ` Andreas Kemnade
2020-11-02 23:56 ` Brad Campbell
2020-11-03 5:56 ` Brad Campbell
2020-11-04 13:20 ` Andreas Kemnade
2020-11-05 2:18 ` Brad Campbell
2020-11-05 4:22 ` Brad Campbell
2020-11-05 4:43 ` Guenter Roeck
2020-11-05 5:05 ` Brad Campbell
2020-11-05 5:26 ` Guenter Roeck
2020-11-05 5:47 ` [PATCH] applesmc: Re-work SMC comms v1 Brad Campbell
2020-11-05 7:26 ` [PATCH] applesmc: Re-work SMC comms v2 Brad Campbell
2020-11-05 7:56 ` Henrik Rydberg
2020-11-05 8:15 ` Andreas Kemnade
2020-11-05 8:30 ` Brad Campbell
2020-11-05 10:31 ` Henrik Rydberg
2020-11-06 16:26 ` Henrik Rydberg
2020-11-06 20:02 ` Henrik Rydberg
2020-11-07 18:31 ` Henrik Rydberg
2020-11-08 0:09 ` Brad Campbell
2020-11-08 8:22 ` Henrik Rydberg
2020-11-08 1:00 ` Brad Campbell [this message]
2020-11-08 8:35 ` [PATCH v3] applesmc: Re-work SMC comms Henrik Rydberg
2020-11-08 10:14 ` Henrik Rydberg
2020-11-08 11:57 ` Brad Campbell
2020-11-08 12:04 ` Henrik Rydberg
2020-11-09 13:06 ` Brad Campbell
2020-11-09 17:08 ` Henrik Rydberg
2020-11-09 22:52 ` Brad Campbell
2020-11-08 16:06 ` Guenter Roeck
2020-11-09 0:25 ` Brad Campbell
2020-11-10 2:04 ` Brad Campbell
2020-11-10 4:55 ` Guenter Roeck
2020-11-10 5:40 ` Brad Campbell
2020-11-10 16:02 ` Guenter Roeck
2020-11-09 8:44 ` Andreas Kemnade
2020-11-09 9:51 ` Brad Campbell
2020-11-11 3:37 ` [PATCH v4 0/1] " Brad Campbell
2020-11-11 4:55 ` [PATCH v1] applesmc: Cleanups on top of re-work comms Brad Campbell
2020-11-11 3:38 ` [PATCH v4 1/1] applesmc: Re-work SMC comms Brad Campbell
2020-11-11 5:56 ` Guenter Roeck
2020-11-11 7:05 ` Brad Campbell
2020-11-11 13:06 ` [PATCH v5 " Brad Campbell
2020-11-11 20:05 ` Henrik Rydberg
2020-11-11 23:28 ` Brad Campbell
2020-11-12 3:08 ` [PATCH v6 " Brad Campbell
2020-11-12 17:20 ` Guenter Roeck
2020-11-06 23:11 ` [PATCH] applesmc: Re-work SMC comms v2 Brad Campbell
2020-11-05 8:12 ` Andreas Kemnade
2020-11-05 16:12 ` Guenter Roeck
2020-11-06 0:02 ` Brad Campbell
2020-11-06 3:08 ` Guenter Roeck
2020-11-09 9:27 ` [PATCH] applesmc: Re-work SMC comms v1 kernel test robot
2020-11-05 9:48 ` [REGRESSION] hwmon: (applesmc) avoid overlong udelay() Arnd Bergmann
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