[PATCH linux-next 0/2] mfd: flexcom: add a driver for Flexcom

[PATCH linux-next 0/2] mfd: flexcom: add a driver for Flexcom

[Cyrille Pitchen]

ChangeLog

v1:
This series of patches a support to the Atmel Flexcom, a wrapper which
integrates an USART, a SPI controller and a TWI controller. Only one
peripheral can be used at a time. The active function is selected though
the Flexcom Mode Register.

Cyrille Pitchen (2):
  mfd: devicetree: add bindings for Atmel Flexcom
  mfd: flexcom: add a driver for Atmel Flexible Serial Communication
    Unit

 .../devicetree/bindings/mfd/atmel-flexcom.txt      | 28 +++++++
 drivers/mfd/Kconfig                                | 11 +++
 drivers/mfd/Makefile                               |  1 +
 drivers/mfd/atmel-flexcom.c                        | 97 ++++++++++++++++++++++
 4 files changed, 137 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/atmel-flexcom.txt
 create mode 100644 drivers/mfd/atmel-flexcom.c

-- 
1.8.2.2

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[PATCH linux-next 1/2] mfd: devicetree: add bindings for Atmel Flexcom

[Cyrille Pitchen]

Signed-off-by: Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 .../devicetree/bindings/mfd/atmel-flexcom.txt      | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/atmel-flexcom.txt

diff --git a/Documentation/devicetree/bindings/mfd/atmel-flexcom.txt b/Documentation/devicetree/bindings/mfd/atmel-flexcom.txt
new file mode 100644
index 0000000..6b1a32e
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/atmel-flexcom.txt
@@ -0,0 +1,28 @@
+* Device tree bindings for Atmel Flexcom (Flexible Serial Communication Unit)
+
+The Atmel Flexcom is just a wrapper which embeds a SPI controller, an I2C
+controller and an USART. Only one function can be used at a time and is chosen
+at boot time according to the device tree.
+
+Required properties:
+- compatible: "atmel,sama5d2-flexcom"
+- reg: shall be the offset/length value for Flexcom dedicated I/O registers
+  (without USART, TWI or SPI registers).
+- clocks: shall be the Flexcom peripheral clock from PMC.
+- #address-cells: should be <1>
+- #size-cells: should be <1>
+- ranges: must be present
+- atmel,flexcom-mode: shall be a string among { "spi", "usart", "i2c", "twi" }.
+  "i2c" and "twi" are synonymous.
+
+Example:
+
+flx0: flexcom@f8034000 {
+	compatible = "atmel,sama5d2-flexcom";
+	reg = <0xf8034000 0x200>;
+	clocks = <&flx0_clk>;
+	#address-cells = <1>;
+	#size-cells = <1>;
+	ranges;
+	atmel,flexcom-mode = "spi";
+};
-- 
1.8.2.2

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Re: [PATCH linux-next 1/2] mfd: devicetree: add bindings for Atmel Flexcom

[Boris Brezillon]

Hi Cyrille,

On Mon, 15 Jun 2015 18:38:04 +0200
Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> wrote:

> Signed-off-by: Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
> ---
>  .../devicetree/bindings/mfd/atmel-flexcom.txt      | 28 ++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/atmel-flexcom.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/atmel-flexcom.txt b/Documentation/devicetree/bindings/mfd/atmel-flexcom.txt
> new file mode 100644
> index 0000000..6b1a32e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/atmel-flexcom.txt
> @@ -0,0 +1,28 @@
> +* Device tree bindings for Atmel Flexcom (Flexible Serial Communication Unit)
> +
> +The Atmel Flexcom is just a wrapper which embeds a SPI controller, an I2C
> +controller and an USART. Only one function can be used at a time and is chosen
> +at boot time according to the device tree.
> +
> +Required properties:
> +- compatible: "atmel,sama5d2-flexcom"
> +- reg: shall be the offset/length value for Flexcom dedicated I/O registers
> +  (without USART, TWI or SPI registers).
> +- clocks: shall be the Flexcom peripheral clock from PMC.
> +- #address-cells: should be <1>
> +- #size-cells: should be <1>
> +- ranges: must be present
> +- atmel,flexcom-mode: shall be a string among { "spi", "usart", "i2c", "twi" }.
> +  "i2c" and "twi" are synonymous.
> +
> +Example:
> +
> +flx0: flexcom@f8034000 {
> +	compatible = "atmel,sama5d2-flexcom";
> +	reg = <0xf8034000 0x200>;
> +	clocks = <&flx0_clk>;
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	ranges;
> +	atmel,flexcom-mode = "spi";
> +};

Since the subdevices are using a set of registers contained by the
flexcom device I would define it like this:

flx0: flexcom@f8034000 {
	compatible = "atmel,sama5d2-flexcom";
	reg = <0xf8034000 0x800>;
	clocks = <&flx0_clk>;
	#address-cells = <1>;
	#size-cells = <1>;
	ranges = <0x0 0xf8034000 0x800>;
	atmel,flexcom-mode = "spi";

	usart@200 {
		reg = <0x200 0x100>;
		/* ... */
	};

	spi@400 {
		reg = <0x400 0x100>;
		/* ... */
	};

	i2c@600 {
		reg = <0x600 0x100>;
		/* ... */
	};
};

Best Regards,

Boris

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Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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[PATCH linux-next 2/2] mfd: flexcom: add a driver for Atmel Flexible Serial Communication Unit

[Cyrille Pitchen]

This driver supports the new Atmel Flexcom. The Flexcom is a wrapper which
integrates one SPI controller, one I2C controller and one USART. Only one
function can be enabled at a time. This driver selects the function once
for all, when the Flexcom is probed, according to the value of the new
"atmel,flexcom-mode" device tree property.

This driver has chosen to present the Flexcom to the system as a MFD so
the implementation is seamless for the existing Atmel SPI, I2C and USART
drivers.

Also the Flexcom embeds FIFOs: the latest patches of the SPI, I2C and
USART drivers take advantage of this new feature.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 drivers/mfd/Kconfig         | 11 +++++
 drivers/mfd/Makefile        |  1 +
 drivers/mfd/atmel-flexcom.c | 97 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+)
 create mode 100644 drivers/mfd/atmel-flexcom.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index aefbbbf..4aebf08 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -60,6 +60,17 @@ config MFD_AAT2870_CORE
 	  additional drivers must be enabled in order to use the
 	  functionality of the device.
 
+config MFD_ATMEL_FLEXCOM
+	tristate "Atmel Flexcom (Flexible Serial Communication Unit)"
+	select MFD_CORE
+	depends on OF
+	help
+	  Select this to get support for Atmel Flexcom. This is a wrapper
+	  which embeds a SPI controller, a I2C controller and a USART. Only
+	  one function can be used at a time. The choice is done at boot time
+	  by the probe function of this MFD driver according to a device tree
+	  property.
+
 config MFD_ATMEL_HLCDC
 	tristate "Atmel HLCDC (High-end LCD Controller)"
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index ea40e07..0705eb2 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -160,6 +160,7 @@ obj-$(CONFIG_MFD_SPMI_PMIC)	+= qcom-spmi-pmic.o
 obj-$(CONFIG_TPS65911_COMPARATOR)	+= tps65911-comparator.o
 obj-$(CONFIG_MFD_TPS65090)	+= tps65090.o
 obj-$(CONFIG_MFD_AAT2870_CORE)	+= aat2870-core.o
+obj-$(CONFIG_MFD_ATMEL_FLEXCOM)	+= atmel-flexcom.o
 obj-$(CONFIG_MFD_ATMEL_HLCDC)	+= atmel-hlcdc.o
 obj-$(CONFIG_MFD_INTEL_MSIC)	+= intel_msic.o
 obj-$(CONFIG_MFD_PALMAS)	+= palmas.o
diff --git a/drivers/mfd/atmel-flexcom.c b/drivers/mfd/atmel-flexcom.c
new file mode 100644
index 0000000..14c35e6
--- /dev/null
+++ b/drivers/mfd/atmel-flexcom.c
@@ -0,0 +1,97 @@
+/*
+ * Driver for Atmel Flexcom
+ *
+ * Copyright (C) 2015 Atmel Corporation
+ *
+ * Author: Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+
+#define FX_MR		0x0
+#define FX_RHR		0x10
+#define FX_THR		0x20
+#define FX_VERSION	0xfc
+
+#define FX_MR_NO_COM	0
+#define FX_MR_USART	1
+#define FX_MR_SPI	2
+#define FX_MR_TWI	3
+
+
+static int atmel_flexcom_probe(struct platform_device *pdev)
+{
+	struct clk *clk;
+	struct resource *res;
+	unsigned char __iomem *map;
+	unsigned int version, mr;
+	const char *mode;
+	int err;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	map = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	err = of_property_read_string(pdev->dev.of_node,
+				      "atmel,flexcom-mode", &mode);
+	if (err)
+		return err;
+
+	if (!strcmp(mode, "usart"))
+		mr = FX_MR_USART;
+	else if (!strcmp(mode, "spi"))
+		mr = FX_MR_SPI;
+	else if (!strcmp(mode, "twi") || !strcmp(mode, "i2c"))
+		mr = FX_MR_TWI;
+	else
+		return -EINVAL;
+
+	clk_prepare_enable(clk);
+	version = __raw_readl(map + FX_VERSION);
+	__raw_writel(mr, map + FX_MR);
+	clk_disable_unprepare(clk);
+
+	dev_info(&pdev->dev, "version: %#x\n", version);
+
+	return of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+}
+
+static const struct of_device_id atmel_flexcom_of_match[] = {
+	{ .compatible = "atmel,sama5d2-flexcom" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
+
+static struct platform_driver atmel_flexcom_driver = {
+	.driver		= {
+		.name	= "atmel_flexcom",
+		.of_match_table = atmel_flexcom_of_match,
+	},
+	.probe		= atmel_flexcom_probe,
+};
+
+module_platform_driver(atmel_flexcom_driver);
+
+MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>");
+MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:atmel_flexcom");
-- 
1.8.2.2

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Re: [PATCH linux-next 2/2] mfd: flexcom: add a driver for Atmel Flexible Serial Communication Unit

[Boris Brezillon]

On Mon, 15 Jun 2015 18:38:05 +0200
Cyrille Pitchen <cyrille.pitchen@atmel.com> wrote:

> This driver supports the new Atmel Flexcom. The Flexcom is a wrapper which
> integrates one SPI controller, one I2C controller and one USART. Only one
> function can be enabled at a time. This driver selects the function once
> for all, when the Flexcom is probed, according to the value of the new
> "atmel,flexcom-mode" device tree property.
> 
> This driver has chosen to present the Flexcom to the system as a MFD so
> the implementation is seamless for the existing Atmel SPI, I2C and USART
> drivers.
> 
> Also the Flexcom embeds FIFOs: the latest patches of the SPI, I2C and
> USART drivers take advantage of this new feature.
> 
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
> ---
>  drivers/mfd/Kconfig         | 11 +++++
>  drivers/mfd/Makefile        |  1 +
>  drivers/mfd/atmel-flexcom.c | 97 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 109 insertions(+)
>  create mode 100644 drivers/mfd/atmel-flexcom.c
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index aefbbbf..4aebf08 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -60,6 +60,17 @@ config MFD_AAT2870_CORE
>  	  additional drivers must be enabled in order to use the
>  	  functionality of the device.
>  
> +config MFD_ATMEL_FLEXCOM
> +	tristate "Atmel Flexcom (Flexible Serial Communication Unit)"
> +	select MFD_CORE
> +	depends on OF
> +	help
> +	  Select this to get support for Atmel Flexcom. This is a wrapper
> +	  which embeds a SPI controller, a I2C controller and a USART. Only
> +	  one function can be used at a time. The choice is done at boot time
> +	  by the probe function of this MFD driver according to a device tree
> +	  property.
> +
>  config MFD_ATMEL_HLCDC
>  	tristate "Atmel HLCDC (High-end LCD Controller)"
>  	select MFD_CORE
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index ea40e07..0705eb2 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -160,6 +160,7 @@ obj-$(CONFIG_MFD_SPMI_PMIC)	+= qcom-spmi-pmic.o
>  obj-$(CONFIG_TPS65911_COMPARATOR)	+= tps65911-comparator.o
>  obj-$(CONFIG_MFD_TPS65090)	+= tps65090.o
>  obj-$(CONFIG_MFD_AAT2870_CORE)	+= aat2870-core.o
> +obj-$(CONFIG_MFD_ATMEL_FLEXCOM)	+= atmel-flexcom.o
>  obj-$(CONFIG_MFD_ATMEL_HLCDC)	+= atmel-hlcdc.o
>  obj-$(CONFIG_MFD_INTEL_MSIC)	+= intel_msic.o
>  obj-$(CONFIG_MFD_PALMAS)	+= palmas.o
> diff --git a/drivers/mfd/atmel-flexcom.c b/drivers/mfd/atmel-flexcom.c
> new file mode 100644
> index 0000000..14c35e6
> --- /dev/null
> +++ b/drivers/mfd/atmel-flexcom.c
> @@ -0,0 +1,97 @@
> +/*
> + * Driver for Atmel Flexcom
> + *
> + * Copyright (C) 2015 Atmel Corporation
> + *
> + * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/clk.h>
> +
> +#define FX_MR		0x0
> +#define FX_RHR		0x10
> +#define FX_THR		0x20
> +#define FX_VERSION	0xfc
> +
> +#define FX_MR_NO_COM	0
> +#define FX_MR_USART	1
> +#define FX_MR_SPI	2
> +#define FX_MR_TWI	3
> +
> +
> +static int atmel_flexcom_probe(struct platform_device *pdev)
> +{
> +	struct clk *clk;
> +	struct resource *res;
> +	unsigned char __iomem *map;
> +	unsigned int version, mr;
> +	const char *mode;
> +	int err;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	map = devm_ioremap_resource(&pdev->dev, res);

If you take the approach I suggested in the DT binding review,
you shouldn't reserve the whole memory region, just the flexcom
part(0x0 to 0x200). 

> +	if (IS_ERR(map))
> +		return PTR_ERR(map);
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
> +	err = of_property_read_string(pdev->dev.of_node,
> +				      "atmel,flexcom-mode", &mode);
> +	if (err)
> +		return err;
> +
> +	if (!strcmp(mode, "usart"))
> +		mr = FX_MR_USART;
> +	else if (!strcmp(mode, "spi"))
> +		mr = FX_MR_SPI;
> +	else if (!strcmp(mode, "twi") || !strcmp(mode, "i2c"))
> +		mr = FX_MR_TWI;
> +	else
> +		return -EINVAL;
> +
> +	clk_prepare_enable(clk);
> +	version = __raw_readl(map + FX_VERSION);
> +	__raw_writel(mr, map + FX_MR);
> +	clk_disable_unprepare(clk);

Is there a good reason to use the __raw versions of the writel/readl
functions ?



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

Re: [PATCH linux-next 2/2] mfd: flexcom: add a driver for Atmel Flexible Serial Communication Unit

[Alexandre Belloni]

Hi,

On 15/06/2015 at 18:38:05 +0200, Cyrille Pitchen wrote :
> +	err = of_property_read_string(pdev->dev.of_node,
> +				      "atmel,flexcom-mode", &mode);
> +	if (err)
> +		return err;
> +
> +	if (!strcmp(mode, "usart"))
> +		mr = FX_MR_USART;
> +	else if (!strcmp(mode, "spi"))
> +		mr = FX_MR_SPI;
> +	else if (!strcmp(mode, "twi") || !strcmp(mode, "i2c"))
> +		mr = FX_MR_TWI;
> +	else
> +		return -EINVAL;
> +
> +	clk_prepare_enable(clk);
> +	version = __raw_readl(map + FX_VERSION);
> +	__raw_writel(mr, map + FX_MR);
> +	clk_disable_unprepare(clk);
> +
> +	dev_info(&pdev->dev, "version: %#x\n", version);
> +

I would also print the selected mode for debugging convenience,
especially if this is used with device tree overlays.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Re: [PATCH linux-next 2/2] mfd: flexcom: add a driver for Atmel Flexible Serial Communication Unit

[Paul Bolle]

Just a nit: a license mismatch.

On Mon, 2015-06-15 at 18:38 +0200, Cyrille Pitchen wrote:
> --- /dev/null
> +++ b/drivers/mfd/atmel-flexcom.c

> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.

This states the license is GPL v2 (or later)

> +MODULE_LICENSE("GPL v2");

According to include/linux/module.h this states the license is (just)
GPL v2. So I think that either the comment at the top of this file or
the ident used in the MODULE_LICENSE() macro needs to change.

Thanks,


Paul Bolle 

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