Re: [PATCH v2 1/6] i2c: s3c2410: Moving I2C interrupt re-configuration code into i2c driver

From: Tomasz Figa
Date: Tue May 06 2014 - 14:37:22 EST

Hi Pankaj,

On 06.05.2014 10:51, Pankaj Dubey wrote:
Let's move I2C interrupt re-configuration code from machine
file exynos.c to I2C driver. Since only Exynos5250, and
Exynos5420 need to do this, added syscon based phandle to
i2c device nodes of respective SoC DT files.

CC: Rob Herring <robh+dt@xxxxxxxxxx>
CC: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
CC: Wolfram Sang <wsa@xxxxxxxxxxxxx>
CC: Russell King <linux@xxxxxxxxxxxxxxxx>
CC: devicetree@xxxxxxxxxxxxxxx
CC: linux-doc@xxxxxxxxxxxxxxx
CC: linux-i2c@xxxxxxxxxxxxxxx
Signed-off-by: Pankaj Dubey <pankaj.dubey@xxxxxxxxxxx>
---
.../devicetree/bindings/arm/samsung/sysreg.txt | 1 +
arch/arm/boot/dts/exynos5.dtsi | 5 ++++
arch/arm/boot/dts/exynos5250.dtsi | 4 +++
arch/arm/boot/dts/exynos5420.dtsi | 4 +++
arch/arm/mach-exynos/exynos.c | 26 -------------------
drivers/i2c/busses/i2c-s3c2410.c | 27 ++++++++++++++++++++
6 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/samsung/sysreg.txt b/Documentation/devicetree/bindings/arm/samsung/sysreg.txt
index 0ab3251..fd71581 100644
--- a/Documentation/devicetree/bindings/arm/samsung/sysreg.txt
+++ b/Documentation/devicetree/bindings/arm/samsung/sysreg.txt
@@ -3,6 +3,7 @@ SAMSUNG S5P/Exynos SoC series System Registers (SYSREG)
Properties:
- compatible : should contain "samsung,<chip name>-sysreg", "syscon";
For Exynos4 SoC series it should be "samsung,exynos4-sysreg", "syscon";
+ For Exynos5 SoC series it should be "samsung,exynos5-sysreg", "syscon";
- reg : offset and length of the register set.

Example:
diff --git a/arch/arm/boot/dts/exynos5.dtsi b/arch/arm/boot/dts/exynos5.dtsi
index 79d0608..3027e37 100644
--- a/arch/arm/boot/dts/exynos5.dtsi
+++ b/arch/arm/boot/dts/exynos5.dtsi
@@ -99,4 +99,9 @@
#size-cells = <0>;
status = "disabled";
};
+
+ sys_reg: syscon@10050000 {
+ compatible = "samsung,exynos5-sysreg", "syscon";
+ reg = <0x10050000 0x400>;
+ };
};
diff --git a/arch/arm/boot/dts/exynos5250.dtsi b/arch/arm/boot/dts/exynos5250.dtsi
index 8d724d5..46f0233 100644
--- a/arch/arm/boot/dts/exynos5250.dtsi
+++ b/arch/arm/boot/dts/exynos5250.dtsi
@@ -285,6 +285,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c0_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

@@ -298,6 +299,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c1_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

@@ -311,6 +313,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c2_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

@@ -324,6 +327,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c3_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
index ff496ad..762128c 100644
--- a/arch/arm/boot/dts/exynos5420.dtsi
+++ b/arch/arm/boot/dts/exynos5420.dtsi
@@ -517,6 +517,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c0_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

@@ -530,6 +531,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c1_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

@@ -543,6 +545,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c2_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

@@ -556,6 +559,7 @@
clock-names = "i2c";
pinctrl-names = "default";
pinctrl-0 = <&i2c3_bus>;
+ samsung,syscon-phandle = <&sys_reg>;
status = "disabled";
};

diff --git a/arch/arm/mach-exynos/exynos.c b/arch/arm/mach-exynos/exynos.c
index 59eb1f1..54ae2e1 100644
--- a/arch/arm/mach-exynos/exynos.c
+++ b/arch/arm/mach-exynos/exynos.c
@@ -293,32 +293,6 @@ void __init exynos_map_pmu(void)

static void __init exynos_dt_machine_init(void)
{
- struct device_node *i2c_np;
- const char *i2c_compat = "samsung,s3c2440-i2c";
- unsigned int tmp;
- int id;
-
- /*
- * Exynos5's legacy i2c controller and new high speed i2c
- * controller have muxed interrupt sources. By default the
- * interrupts for 4-channel HS-I2C controller are enabled.
- * If node for first four channels of legacy i2c controller
- * are available then re-configure the interrupts via the
- * system register.
- */
- if (soc_is_exynos5()) {
- for_each_compatible_node(i2c_np, NULL, i2c_compat) {
- if (of_device_is_available(i2c_np)) {
- id = of_alias_get_id(i2c_np, "i2c");
- if (id < 4) {
- tmp = readl(EXYNOS5_SYS_I2C_CFG);
- writel(tmp & ~(0x1 << id),
- EXYNOS5_SYS_I2C_CFG);
- }
- }
- }
- }
-
exynos_map_pmu();

if (!soc_is_exynos5440())
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index ae44910..0420150 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -39,6 +39,8 @@
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/pinctrl/consumer.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>

#include <asm/irq.h>

@@ -91,6 +93,9 @@
/* Max time to wait for bus to become idle after a xfer (in us) */
#define S3C2410_IDLE_TIMEOUT 5000

+/* Exynos5 Sysreg offset */
+#define EXYNOS5_SYS_I2C_CFG 0x0234
+
/* i2c controller state */
enum s3c24xx_i2c_state {
STATE_IDLE,
@@ -127,6 +132,7 @@ struct s3c24xx_i2c {
#if defined(CONFIG_ARM_S3C24XX_CPUFREQ)
struct notifier_block freq_transition;
#endif
+ struct regmap *sysreg;
};

static struct platform_device_id s3c24xx_driver_ids[] = {
@@ -1075,6 +1081,8 @@ static void
s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
{
struct s3c2410_platform_i2c *pdata = i2c->pdata;
+ unsigned int tmp;
+ int id;

if (!np)
return;
@@ -1084,6 +1092,25 @@ s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
of_property_read_u32(np, "samsung,i2c-slave-addr", &pdata->slave_addr);
of_property_read_u32(np, "samsung,i2c-max-bus-freq",
(u32 *)&pdata->frequency);
+ /*
+ * Exynos5's legacy i2c controller and new high speed i2c
+ * controller have muxed interrupt sources. By default the
+ * interrupts for 4-channel HS-I2C controller are enabled.
+ * If node for first four channels of legacy i2c controller
+ * are available then re-configure the interrupts via the
+ * system register.
+ */
+ id = of_alias_get_id(np, "i2c");
+ i2c->sysreg = syscon_regmap_lookup_by_phandle(np,
+ "samsung,syscon-phandle");
+ if (IS_ERR(i2c->sysreg)) {
+ i2c->sysreg = NULL;

NULL shouldn't be considered for pointers using the ERR_PTR() convention, so you should just preserve the value returned by syscon_regmap_lookup_by_phandle() here.

Also, the driver seems to do this only once in probe, so maybe you should simply use a local variable here, without storing the regmap in i2c struct.

+ /* As this is not compulsary do not return error */

Is it? Will the driver work normally without interrupts in this case?

Also, typo: s/compulsary/compulsory/

+ pr_info("i2c-%d skipping re-configuration of interrutps\n", id);
+ return;
+ }
+ regmap_read(i2c->sysreg, EXYNOS5_SYS_I2C_CFG, &tmp);
+ regmap_write(i2c->sysreg, EXYNOS5_SYS_I2C_CFG, tmp & ~(0x1 << id));

You could use regmap_update_bits() [1] here instead, with mask set to BIT(id) and val set to 0.

[1] http://lxr.free-electrons.com/source/drivers/base/regmap/regmap.c#L1977

Best regards,
Tomasz
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