On Mon, 07 Dec 2015, Damien Riegel wrote:

On Mon, Dec 07, 2015 at 09:40:20AM +0000, Lee Jones wrote:

quoted

On Mon, 30 Nov 2015, Damien Riegel wrote:

quoted

Currently syscon has a fixed configuration of 32 bits for register and
values widths. In some cases, it would be desirable to be able to
customize the value width.

For example, certain boards (like the ones manufactured by Technologic
Systems) have a FPGA that is memory-mapped, but its registers are only
16-bit wide.

This patch adds an optional "reg-io-width" DT binding for syscon that
allows to change the width for the data bus (i.e. val_bits). If this
property is provided, it will also set the register stride to
reg-io-width's value. If not provided, the default configuration is
used.

Signed-off-by: Damien Riegel <redacted>
---
 Documentation/devicetree/bindings/mfd/syscon.txt |  4 ++++
 drivers/mfd/syscon.c                             | 13 +++++++++++++
 2 files changed, 17 insertions(+)

Applied, thanks.

Hi Lee,

Good to see this patch applied. What's going on now with the other
patches of this serie ? How should I handle them ?

Are there any build dependencies between them?

quoted

quoted

diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
index fe8150b..408f768 100644
--- a/Documentation/devicetree/bindings/mfd/syscon.txt
+++ b/Documentation/devicetree/bindings/mfd/syscon.txt

@@ -13,6 +13,10 @@ Required properties:
 - compatible: Should contain "syscon".
 - reg: the register region can be accessed from syscon
 
+Optional property:
+- reg-io-width: the size (in bytes) of the IO accesses that should be
+  performed on the device.
+
 Examples:
 gpr: iomuxc-gpr at 020e0000 {
 	compatible = "fsl,imx6q-iomuxc-gpr", "syscon";

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index 176bf0f..b7aabee 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c

@@ -47,6 +47,7 @@ static struct syscon *of_syscon_register(struct device_node *np)
 	struct syscon *syscon;
 	struct regmap *regmap;
 	void __iomem *base;
+	u32 reg_io_width;
 	int ret;
 	struct regmap_config syscon_config = syscon_regmap_config;
 

@@ -69,6 +70,18 @@ static struct syscon *of_syscon_register(struct device_node *np)
 	 else if (of_property_read_bool(np, "little-endian"))
 		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
 
+	/*
+	 * search for reg-io-width property in DT. If it is not provided,
+	 * default to 4 bytes. regmap_init_mmio will return an error if values
+	 * are invalid so there is no need to check them here.
+	 */
+	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
+	if (ret)
+		reg_io_width = 4;
+
+	syscon_config.reg_stride = reg_io_width;
+	syscon_config.val_bits = reg_io_width * 8;
+
 	regmap = regmap_init_mmio(NULL, base, &syscon_config);
 	if (IS_ERR(regmap)) {
 		pr_err("regmap init failed\n");

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org ? Open source software for ARM SoCs
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