linux-kernel - [PATCH v4 2/2] checks: Improve i2c reg property checking

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Message-Id: <20200622031005.1890039-3-joel@jms.id.au>
Date:   Mon, 22 Jun 2020 12:40:05 +0930
From:   Joel Stanley <joel@....id.au>
To:     devicetree-compiler@...r.kernel.org,
        David Gibson <david@...son.dropbear.id.au>
Cc:     linux-kernel@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH v4 2/2] checks: Improve i2c reg property checking

The i2c bindings in the kernel tree describe support for 10 bit
addressing, which must be indicated with the I2C_TEN_BIT_ADDRESS flag.
When this is set the address can be up to 10 bits. When it is not set
the address is a maximum of 7 bits.

See Documentation/devicetree/bindings/i2c/i2c.txt.

Take into account this flag when checking the address is valid.

Signed-off-by: Joel Stanley <joel@....id.au>
---
v2: Mask reg when checking the 10-bit size
v3: Fix test
v4: Add U to define
---
 checks.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/checks.c b/checks.c
index 69b0156c940c..b7955dbd71ca 100644
--- a/checks.c
+++ b/checks.c
@@ -1023,6 +1023,7 @@ static void check_i2c_bus_bridge(struct check *c, struct dt_info *dti, struct no
 WARNING(i2c_bus_bridge, check_i2c_bus_bridge, NULL, &addr_size_cells);
 
 #define I2C_OWN_SLAVE_ADDRESS	(1U << 30)
+#define I2C_TEN_BIT_ADDRESS	(1U << 31)
 
 static void check_i2c_bus_reg(struct check *c, struct dt_info *dti, struct node *node)
 {
@@ -1057,10 +1058,13 @@ static void check_i2c_bus_reg(struct check *c, struct dt_info *dti, struct node
 		reg = fdt32_to_cpu(*(cells++));
 		/* Ignore I2C_OWN_SLAVE_ADDRESS */
 		reg &= ~I2C_OWN_SLAVE_ADDRESS;
-		if (reg > 0x3ff)
+
+		if ((reg & I2C_TEN_BIT_ADDRESS) && ((reg & ~I2C_TEN_BIT_ADDRESS) > 0x3ff))
 			FAIL_PROP(c, dti, node, prop, "I2C address must be less than 10-bits, got \"0x%x\"",
 				  reg);
-
+		else if (reg > 0x7f)
+			FAIL_PROP(c, dti, node, prop, "I2C address must be less than 7-bits, got \"0x%x\". Set I2C_TEN_BIT_ADDRESS for 10 bit addresses or fix the property",
+				  reg);
 	}
 }
 WARNING(i2c_bus_reg, check_i2c_bus_reg, NULL, &reg_format, &i2c_bus_bridge);
-- 
2.27.0