[2.6.29-rc7][take #2][PATCH 0/3] ARM: OMAP: Add command line option for I2C bus speed

[2.6.29-rc7][take #2][PATCH 0/3] ARM: OMAP: Add command line option for I2C bus speed

[Jarkko Nikula]

Hi

Tony, I added kernel-parameters.txt change to the patches 2 and 3. Otherwise
set is the same than currently in linux-omap. Set is generated on top of
mainline version 2.6.29-rc7. Earlier discussion was

http://marc.info/?l=linux-omap&m=123635604511892&w=2


-- 
Jarkko

[2.6.29-rc7][take #2][PATCH 1/3] ARM: OMAP: Add documentation for function omap_register_i2c_bus

[Jarkko Nikula]

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
---
 arch/arm/plat-omap/i2c.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index 467531e..3e95954 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -119,6 +119,15 @@ static void __init omap_i2c_mux_pins(int bus)
 	omap_cfg_reg(scl);
 }
 
+/**
+ * omap_register_i2c_bus - register I2C bus with device descriptors
+ * @bus_id: bus id counting from number 1
+ * @clkrate: clock rate of the bus in kHz
+ * @info: pointer into I2C device descriptor table or NULL
+ * @len: number of descriptors in the table
+ *
+ * Returns 0 on success or an error code.
+ */
 int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
 			  struct i2c_board_info const *info,
 			  unsigned len)
-- 
1.6.1.3

[2.6.29-rc7][take #2][PATCH 2/3] ARM: OMAP: Add command line option for I2C bus speed

[Jarkko Nikula]

This patch adds a new command line option "i2c_bus=bus_id,clkrate" into
I2C bus registration helper. Purpose of the option is to override the
default board specific bus speed which is supplied by the
omap_register_i2c_bus.

The default bus speed is typically set to speed of slowest I2C chip on the
bus and overriding allow to use some experimental configurations or updated
chip versions without any kernel modifications.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
---
 Documentation/kernel-parameters.txt |    4 ++
 arch/arm/plat-omap/i2c.c            |   54 ++++++++++++++++++++++++++++------
 2 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 54f21a5..d775076 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -830,6 +830,10 @@ and is between 256 and 4096 characters. It is defined in the file
 	hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
 			       terminal devices. Valid values: 0..8
 
+	i2c_bus=	[HW] Override the default board specific I2C bus speed
+			     Format:
+			     <bus_id>,<clkrate>
+
 	i8042.debug	[HW] Toggle i8042 debug mode
 	i8042.direct	[HW] Put keyboard port into non-translated mode
 	i8042.dumbkbd	[HW] Pretend that controller can only read data from
diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index 3e95954..aa70e43 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -119,6 +119,46 @@ static void __init omap_i2c_mux_pins(int bus)
 	omap_cfg_reg(scl);
 }
 
+static int __init omap_i2c_nr_ports(void)
+{
+	int ports = 0;
+
+	if (cpu_class_is_omap1())
+		ports = 1;
+	else if (cpu_is_omap24xx())
+		ports = 2;
+	else if (cpu_is_omap34xx())
+		ports = 3;
+
+	return ports;
+}
+
+/**
+ * omap_i2c_bus_setup - Process command line options for the I2C bus speed
+ * @str: String of options
+ *
+ * This function allow to override the default I2C bus speed for given I2C
+ * bus with a command line option.
+ *
+ * Format: i2c_bus=bus_id,clkrate (in kHz)
+ *
+ * Returns 1 on success, 0 otherwise.
+ */
+static int __init omap_i2c_bus_setup(char *str)
+{
+	int ports;
+	int ints[3];
+
+	ports = omap_i2c_nr_ports();
+	get_options(str, 3, ints);
+	if (ints[0] < 2 || ints[1] < 1 || ints[1] > ports)
+		return 0;
+	i2c_rate[ints[1] - 1] = ints[2];
+
+	return 1;
+}
+__setup("i2c_bus=", omap_i2c_bus_setup);
+
 /**
  * omap_register_i2c_bus - register I2C bus with device descriptors
  * @bus_id: bus id counting from number 1
@@ -132,19 +172,12 @@ int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
 			  struct i2c_board_info const *info,
 			  unsigned len)
 {
-	int ports, err;
+	int err;
 	struct platform_device *pdev;
 	struct resource *res;
 	resource_size_t base, irq;
 
-	if (cpu_class_is_omap1())
-		ports = 1;
-	else if (cpu_is_omap24xx())
-		ports = 2;
-	else if (cpu_is_omap34xx())
-		ports = 3;
-
-	BUG_ON(bus_id < 1 || bus_id > ports);
+	BUG_ON(bus_id < 1 || bus_id > omap_i2c_nr_ports());
 
 	if (info) {
 		err = i2c_register_board_info(bus_id, info, len);
@@ -153,7 +186,8 @@ int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
 	}
 
 	pdev = &omap_i2c_devices[bus_id - 1];
-	*(u32 *)pdev->dev.platform_data = clkrate;
+	if (i2c_rate[bus_id - 1] == 0)
+		i2c_rate[bus_id - 1] = clkrate;
 
 	if (bus_id == 1) {
 		res = pdev->resource;
-- 
1.6.1.3

[2.6.29-rc7][take #2][PATCH 3/3] ARM: OMAP: Add method to register additional I2C busses on the command line

[Jarkko Nikula]

This patch extends command line option "i2c_bus=bus_id,clkrate" so that
it allow to register additional I2C busses that are not registered with
omap_register_i2c_bus from board initialization code.

Purpose of this is to register additional board busses which are routed
to external connectors only without any on board I2C devices.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
---
 Documentation/kernel-parameters.txt |    2 +
 arch/arm/plat-omap/i2c.c            |   73 +++++++++++++++++++++++++----------
 2 files changed, 54 insertions(+), 21 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index d775076..ef9827f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -831,6 +831,8 @@ and is between 256 and 4096 characters. It is defined in the file
 			       terminal devices. Valid values: 0..8
 
 	i2c_bus=	[HW] Override the default board specific I2C bus speed
+			     or register an additional I2C bus that is not
+			     registered from board initialization code.
 			     Format:
 			     <bus_id>,<clkrate>
 
diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index aa70e43..a303071 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -98,6 +98,8 @@ static const int omap34xx_pins[][2] = {
 static const int omap34xx_pins[][2] = {};
 #endif
 
+#define OMAP_I2C_CMDLINE_SETUP	(BIT(31))
+
 static void __init omap_i2c_mux_pins(int bus)
 {
 	int scl, sda;
@@ -133,6 +135,31 @@ static int __init omap_i2c_nr_ports(void)
 	return ports;
 }
 
+static int __init omap_i2c_add_bus(int bus_id)
+{
+	struct platform_device *pdev;
+	struct resource *res;
+	resource_size_t base, irq;
+
+	pdev = &omap_i2c_devices[bus_id - 1];
+	if (bus_id == 1) {
+		res = pdev->resource;
+		if (cpu_class_is_omap1()) {
+			base = OMAP1_I2C_BASE;
+			irq = INT_I2C;
+		} else {
+			base = OMAP2_I2C_BASE1;
+			irq = INT_24XX_I2C1_IRQ;
+		}
+		res[0].start = base;
+		res[0].end = base + OMAP_I2C_SIZE;
+		res[1].start = irq;
+	}
+
+	omap_i2c_mux_pins(bus_id - 1);
+	return platform_device_register(pdev);
+}
+
 /**
  * omap_i2c_bus_setup - Process command line options for the I2C bus speed
  * @str: String of options
@@ -154,11 +181,33 @@ static int __init omap_i2c_bus_setup(char *str)
 	if (ints[0] < 2 || ints[1] < 1 || ints[1] > ports)
 		return 0;
 	i2c_rate[ints[1] - 1] = ints[2];
+	i2c_rate[ints[1] - 1] |= OMAP_I2C_CMDLINE_SETUP;
 
 	return 1;
 }
 __setup("i2c_bus=", omap_i2c_bus_setup);
 
+/*
+ * Register busses defined in command line but that are not registered with
+ * omap_register_i2c_bus from board initialization code.
+ */
+static int __init omap_register_i2c_bus_cmdline(void)
+{
+	int i, err = 0;
+
+	for (i = 0; i < ARRAY_SIZE(i2c_rate); i++)
+		if (i2c_rate[i] & OMAP_I2C_CMDLINE_SETUP) {
+			i2c_rate[i] &= ~OMAP_I2C_CMDLINE_SETUP;
+			err = omap_i2c_add_bus(i + 1);
+			if (err)
+				goto out;
+		}
+
+out:
+	return err;
+}
+subsys_initcall(omap_register_i2c_bus_cmdline);
+
 /**
  * omap_register_i2c_bus - register I2C bus with device descriptors
  * @bus_id: bus id counting from number 1
@@ -173,9 +222,6 @@ int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
 			  unsigned len)
 {
 	int err;
-	struct platform_device *pdev;
-	struct resource *res;
-	resource_size_t base, irq;
 
 	BUG_ON(bus_id < 1 || bus_id > omap_i2c_nr_ports());
 
@@ -185,24 +231,9 @@ int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
 			return err;
 	}
 
-	pdev = &omap_i2c_devices[bus_id - 1];
-	if (i2c_rate[bus_id - 1] == 0)
+	if (!i2c_rate[bus_id - 1])
 		i2c_rate[bus_id - 1] = clkrate;
+	i2c_rate[bus_id - 1] &= ~OMAP_I2C_CMDLINE_SETUP;
 
-	if (bus_id == 1) {
-		res = pdev->resource;
-		if (cpu_class_is_omap1()) {
-			base = OMAP1_I2C_BASE;
-			irq = INT_I2C;
-		} else {
-			base = OMAP2_I2C_BASE1;
-			irq = INT_24XX_I2C1_IRQ;
-		}
-		res[0].start = base;
-		res[0].end = base + OMAP_I2C_SIZE;
-		res[1].start = irq;
-	}
-
-	omap_i2c_mux_pins(bus_id - 1);
-	return platform_device_register(pdev);
+	return omap_i2c_add_bus(bus_id);
 }
-- 
1.6.1.3

Re: [2.6.29-rc7][take #2][PATCH 0/3] ARM: OMAP: Add command line option for I2C bus speed

[Tony Lindgren]

* Jarkko Nikula <jarkko.nikula@nokia.com> [090309 06:46]:
> Hi
> 
> Tony, I added kernel-parameters.txt change to the patches 2 and 3. Otherwise
> set is the same than currently in linux-omap. Set is generated on top of
> mainline version 2.6.29-rc7. Earlier discussion was
> 
> http://marc.info/?l=linux-omap&m=123635604511892&w=2

Thanks, they look OK to me. Can you please reply to that earlier thread
with these updated patches, and add linux-i2c@vger.kernel.org to Cc?
Then the I2C people can give their comments on the cmdline option.

Regards,

Tony

[2.6.29-rc7][take #2][PATCH 0/3] ARM: OMAP: Add command line option for I2C bus speed

[Jarkko Nikula]

Hi

These patches are for linux-omap but we want to wide discussion also to
linux-i2c is the new command line option "i2c_bus=bus_id,clkrate" generic
enough to be used for other architectures as well in the future. Patches
are generated on top of mainline 2.6.29-rc7.

Purpose of this command line option is to both allow to override the default
board specific bus speed (patch 2) and register additional busses that
are not registered from board initialization code (patch 3).

Example for patch 2 would be the case where some on board component is upgraded
and which allows to use e.g. higher clock rate on the bus without other major
board changes.

Patch 3 can have more practical use however. E.g. second I2C bus on TI
BeagleBoard doesn't have on board components and thus it is not registered
by default with omap_register_i2c_bus. This bus is routed to expansion pin
header so with this patch it is able to register dynamically when needed.

These patches are previously discussed in these threads:

http://marc.info/?l=linux-omap&m=123635604511892&w=2
http://marc.info/?l=linux-omap&m=123661915517228&w=2


-- 
Jarkko