[PATCH] i2c: aspeed: disable additional device addresses on ast2[56]xx

[Zev Weiss]

The ast25xx and ast26xx have, respectively, two and three configurable
slave device addresses to the ast24xx's one.  We only support using
one at a time, but the others may come up in an indeterminate state
depending on hardware/bootloader behavior, so we need to make sure we
disable them so as to avoid ending up with phantom devices on the bus.

Signed-off-by: Zev Weiss <zev at bewilderbeest.net>
---
 drivers/i2c/busses/i2c-aspeed.c | 50 +++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index a7be6f24450b..20028a7a9f67 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -117,6 +117,8 @@
 
 /* 0x18 : I2CD Slave Device Address Register   */
 #define ASPEED_I2CD_DEV_ADDR_MASK			GENMASK(6, 0)
+#define ASPEED_I2CD_DEV_ADDR2_ENABLE			BIT(15)
+#define ASPEED_I2CD_DEV_ADDR3_ENABLE			BIT(23)
 
 enum aspeed_i2c_master_state {
 	ASPEED_I2C_MASTER_INACTIVE,
@@ -139,6 +141,16 @@ enum aspeed_i2c_slave_state {
 	ASPEED_I2C_SLAVE_STOP,
 };
 
+struct aspeed_i2c_model {
+	u32 (*get_clk_reg_val)(struct device *dev, u32 divisor);
+
+	/*
+	 * Some models support multiple device addresses -- we only support
+	 * using one, but we need to disable the others if they're present.
+	 */
+	unsigned int num_device_addrs;
+};
+
 struct aspeed_i2c_bus {
 	struct i2c_adapter		adap;
 	struct device			*dev;
@@ -147,8 +159,7 @@ struct aspeed_i2c_bus {
 	/* Synchronizes I/O mem access to base. */
 	spinlock_t			lock;
 	struct completion		cmd_complete;
-	u32				(*get_clk_reg_val)(struct device *dev,
-							   u32 divisor);
+	const struct aspeed_i2c_model	*model;
 	unsigned long			parent_clk_frequency;
 	u32				bus_frequency;
 	/* Transaction state. */
@@ -726,6 +737,13 @@ static void __aspeed_i2c_reg_slave(struct aspeed_i2c_bus *bus, u16 slave_addr)
 	addr_reg_val = readl(bus->base + ASPEED_I2C_DEV_ADDR_REG);
 	addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR_MASK;
 	addr_reg_val |= slave_addr & ASPEED_I2CD_DEV_ADDR_MASK;
+
+	/* Disable additional addresses on hardware that has them. */
+	if (bus->model->num_device_addrs > 1)
+		addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR2_ENABLE;
+	if (bus->model->num_device_addrs > 2)
+		addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR3_ENABLE;
+
 	writel(addr_reg_val, bus->base + ASPEED_I2C_DEV_ADDR_REG);
 
 	/* Turn on slave mode. */
@@ -863,6 +881,11 @@ static u32 aspeed_i2c_24xx_get_clk_reg_val(struct device *dev, u32 divisor)
 	return aspeed_i2c_get_clk_reg_val(dev, GENMASK(2, 0), divisor);
 }
 
+static const struct aspeed_i2c_model aspeed_i2c_24xx_bus = {
+	.get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val,
+	.num_device_addrs = 1,
+};
+
 static u32 aspeed_i2c_25xx_get_clk_reg_val(struct device *dev, u32 divisor)
 {
 	/*
@@ -872,6 +895,16 @@ static u32 aspeed_i2c_25xx_get_clk_reg_val(struct device *dev, u32 divisor)
 	return aspeed_i2c_get_clk_reg_val(dev, GENMASK(3, 0), divisor);
 }
 
+static const struct aspeed_i2c_model aspeed_i2c_25xx_bus = {
+	.get_clk_reg_val = aspeed_i2c_25xx_get_clk_reg_val,
+	.num_device_addrs = 2,
+};
+
+static const struct aspeed_i2c_model aspeed_i2c_26xx_bus = {
+	.get_clk_reg_val = aspeed_i2c_25xx_get_clk_reg_val,
+	.num_device_addrs = 3,
+};
+
 /* precondition: bus.lock has been acquired. */
 static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
 {
@@ -882,7 +915,7 @@ static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
 	clk_reg_val &= (ASPEED_I2CD_TIME_TBUF_MASK |
 			ASPEED_I2CD_TIME_THDSTA_MASK |
 			ASPEED_I2CD_TIME_TACST_MASK);
-	clk_reg_val |= bus->get_clk_reg_val(bus->dev, divisor);
+	clk_reg_val |= bus->model->get_clk_reg_val(bus->dev, divisor);
 	writel(clk_reg_val, bus->base + ASPEED_I2C_AC_TIMING_REG1);
 	writel(ASPEED_NO_TIMEOUT_CTRL, bus->base + ASPEED_I2C_AC_TIMING_REG2);
 
@@ -946,15 +979,15 @@ static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus)
 static const struct of_device_id aspeed_i2c_bus_of_table[] = {
 	{
 		.compatible = "aspeed,ast2400-i2c-bus",
-		.data = aspeed_i2c_24xx_get_clk_reg_val,
+		.data = &aspeed_i2c_24xx_bus,
 	},
 	{
 		.compatible = "aspeed,ast2500-i2c-bus",
-		.data = aspeed_i2c_25xx_get_clk_reg_val,
+		.data = &aspeed_i2c_25xx_bus,
 	},
 	{
 		.compatible = "aspeed,ast2600-i2c-bus",
-		.data = aspeed_i2c_25xx_get_clk_reg_val,
+		.data = &aspeed_i2c_26xx_bus,
 	},
 	{ },
 };
@@ -1002,10 +1035,9 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
 
 	match = of_match_node(aspeed_i2c_bus_of_table, pdev->dev.of_node);
 	if (!match)
-		bus->get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val;
+		bus->model = &aspeed_i2c_24xx_bus;
 	else
-		bus->get_clk_reg_val = (u32 (*)(struct device *, u32))
-				match->data;
+		bus->model = match->data;
 
 	/* Initialize the I2C adapter */
 	spin_lock_init(&bus->lock);
-- 
2.28.0