Re: [PATCH v7 2/6] mfd: syscon: add a DT property to set value width
From: Lee Jones <hidden>
Date: 2015-12-07 09:40:46
Also in:
linux-arm-kernel, linux-watchdog, lkml
On Mon, 30 Nov 2015, Damien Riegel wrote:
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.
quoted hunk ↗ jump to hunk
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@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", ®_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 Follow Linaro: Facebook | Twitter | Blog