[PATCH 2/4] mfd: workaround: add companion chip in 88pm80x

[Qiao Zhou <zhouqiao-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>]

in hw design, 800 is mainly for pmic control, while 805 for audio.
but there are 3 registers which controls class D speaker property,
and they are defined in 800 i2c client domain. so 805 codec driver
needs to use 800 i2c client to access class D speaker reg for
audio path management. so add this workaround for the purpose to
let 805 access 800 i2c in some scenario.

Signed-off-by: Qiao Zhou <zhouqiao-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
---
 drivers/mfd/88pm80x-i2c.c   |   28 ++++++++++++++++++++++++++++
 include/linux/mfd/88pm80x.h |    1 +
 2 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/drivers/mfd/88pm80x-i2c.c b/drivers/mfd/88pm80x-i2c.c
index fe37900..81e7aab 100644
--- a/drivers/mfd/88pm80x-i2c.c
+++ b/drivers/mfd/88pm80x-i2c.c
@@ -21,6 +21,12 @@
 #include <linux/uaccess.h>
 #include <linux/err.h>
 
+/*
+ * workaround: some registers needed by pm805 are defined in pm800, so
+ * need to use this global variable to maintain the relation between
+ * pm800 and pm805. would remove it after HW chip fixes the issue.
+ */
+static struct pm80x_chip *g_pm80x_chip;
 
 const struct regmap_config pm80x_regmap_config = {
 	.reg_bits = 8,
@@ -151,6 +157,19 @@ int __devinit pm80x_init(struct i2c_client *client,
 
 	device_init_wakeup(&client->dev, 1);
 
+	/*
+	 * workaround: set g_pm80x_chip to the first probed chip. if the
+	 * second chip is probed, just point to the companion to each
+	 * other so that pm805 can access those specific register. would
+	 * remove it after HW chip fixes the issue.
+	 */
+	if (!g_pm80x_chip)
+		g_pm80x_chip = chip;
+	else {
+		chip->companion = g_pm80x_chip->client;
+		g_pm80x_chip->companion = chip->client;
+	}
+
 	return 0;
 
 err_chip_id:
@@ -164,6 +183,15 @@ int __devexit pm80x_deinit(struct i2c_client *client)
 {
 	struct pm80x_chip *chip = i2c_get_clientdata(client);
 
+	/*
+	 * workaround: clear the dependency between pm800 and pm805.
+	 * would remove it after HW chip fixes the issue.
+	 */
+	if (g_pm80x_chip->companion)
+		g_pm80x_chip->companion = NULL;
+	else
+		g_pm80x_chip = NULL;
+
 	regmap_exit(chip->regmap);
 	devm_kfree(&client->dev, chip);
 
diff --git a/include/linux/mfd/88pm80x.h b/include/linux/mfd/88pm80x.h
index 115348a..217a55c 100644
--- a/include/linux/mfd/88pm80x.h
+++ b/include/linux/mfd/88pm80x.h
@@ -479,6 +479,7 @@ struct pm80x_chip {
 	struct pm80x_subchip *subchip;
 	struct device *dev;
 	struct i2c_client *client;
+	struct i2c_client *companion;
 	struct regmap *regmap;
 	struct regmap_irq_chip *regmap_irq_chip;
 	struct regmap_irq_chip_data *irq_data;
-- 
1.7.0.4