linux-kernel - Applied "regulator: twl: Make sure we have access to powerbus before trying to write to it" to the regulator tree

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Message-Id: <E1akoEz-0007Ky-9d@finisterre>
Date:	Tue, 29 Mar 2016 00:39:05 -0700
From:	Mark Brown <broonie@...nel.org>
To:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Applied "regulator: twl: Make sure we have access to powerbus before trying to write to it" to the regulator tree

The patch

   regulator: twl: Make sure we have access to powerbus before trying to write to it

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 2330b05c095bdeaaf1261c54cd2d4b9127496996 Mon Sep 17 00:00:00 2001
From: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
Date: Sat, 26 Mar 2016 10:28:13 +0200
Subject: [PATCH] regulator: twl: Make sure we have access to powerbus before
 trying to write to it

According to the TRM, we need to enable i2c access to powerbus before
writing to it. Also, a new write to powerbus should not be attempted if
there is a pending transfer. The current code does not implement that
functionality and while there are no known problems caused by that, it is
better to follow what TRM says.

Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/regulator/twl-regulator.c | 78 +++++++++++++++++++++++++++++++++++----
 1 file changed, 70 insertions(+), 8 deletions(-)

diff --git a/drivers/regulator/twl-regulator.c b/drivers/regulator/twl-regulator.c
index 955a6fb1355c..aad748b00e1a 100644
--- a/drivers/regulator/twl-regulator.c
+++ b/drivers/regulator/twl-regulator.c
@@ -21,7 +21,7 @@
 #include <linux/regulator/machine.h>
 #include <linux/regulator/of_regulator.h>
 #include <linux/i2c/twl.h>
-
+#include <linux/delay.h>
 
 /*
  * The TWL4030/TW5030/TPS659x0/TWL6030 family chips include power management, a
@@ -188,6 +188,74 @@ static int twl6030reg_is_enabled(struct regulator_dev *rdev)
 	return grp && (val == TWL6030_CFG_STATE_ON);
 }
 
+#define PB_I2C_BUSY	BIT(0)
+#define PB_I2C_BWEN	BIT(1)
+
+/* Wait until buffer empty/ready to send a word on power bus. */
+static int twl4030_wait_pb_ready(void)
+{
+
+	int	ret;
+	int	timeout = 10;
+	u8	val;
+
+	do {
+		ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val,
+				      TWL4030_PM_MASTER_PB_CFG);
+		if (ret < 0)
+			return ret;
+
+		if (!(val & PB_I2C_BUSY))
+			return 0;
+
+		mdelay(1);
+		timeout--;
+	} while (timeout);
+
+	return -ETIMEDOUT;
+}
+
+/* Send a word over the powerbus */
+static int twl4030_send_pb_msg(unsigned msg)
+{
+	u8	val;
+	int	ret;
+
+	/* save powerbus configuration */
+	ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val,
+			      TWL4030_PM_MASTER_PB_CFG);
+	if (ret < 0)
+		return ret;
+
+	/* Enable i2c access to powerbus */
+	ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val | PB_I2C_BWEN,
+			       TWL4030_PM_MASTER_PB_CFG);
+	if (ret < 0)
+		return ret;
+
+	ret = twl4030_wait_pb_ready();
+	if (ret < 0)
+		return ret;
+
+	ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, msg >> 8,
+			       TWL4030_PM_MASTER_PB_WORD_MSB);
+	if (ret < 0)
+		return ret;
+
+	ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, msg & 0xff,
+			       TWL4030_PM_MASTER_PB_WORD_LSB);
+	if (ret < 0)
+		return ret;
+
+	ret = twl4030_wait_pb_ready();
+	if (ret < 0)
+		return ret;
+
+	/* Restore powerbus configuration */
+	return twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val,
+				TWL_MODULE_PM_MASTER);
+}
+
 static int twl4030reg_enable(struct regulator_dev *rdev)
 {
 	struct twlreg_info	*info = rdev_get_drvdata(rdev);
@@ -324,13 +392,7 @@ static int twl4030reg_set_mode(struct regulator_dev *rdev, unsigned mode)
 	if (!(status & (P3_GRP_4030 | P2_GRP_4030 | P1_GRP_4030)))
 		return -EACCES;
 
-	status = twl_i2c_write_u8(TWL_MODULE_PM_MASTER,
-			message >> 8, TWL4030_PM_MASTER_PB_WORD_MSB);
-	if (status < 0)
-		return status;
-
-	return twl_i2c_write_u8(TWL_MODULE_PM_MASTER,
-			message & 0xff, TWL4030_PM_MASTER_PB_WORD_LSB);
+	return twl4030_send_pb_msg(message);
 }
 
 static int twl6030reg_set_mode(struct regulator_dev *rdev, unsigned mode)
-- 
2.8.0.rc3