[PATCH v2 0/2] clk: at91: add new driver for Flexcom

[PATCH v2 0/2] clk: at91: add new driver for Flexcom

[Cyrille Pitchen]

ChangeLog

v2:
- fix commit message

v1:
This series of patches introduces a new driver for the Atmel Flexcom.

Cyrille Pitchen (2):
  clk: at91: add a new compatible string for Flexcom in the DT
    documentation
  clk: at91: add Flexcom clock

 .../devicetree/bindings/clock/at91-clock.txt       |  20 +++
 arch/arm/mach-at91/Kconfig                         |   3 +
 drivers/clk/at91/Makefile                          |   1 +
 drivers/clk/at91/clk-flexcom.c                     | 160 +++++++++++++++++++++
 4 files changed, 184 insertions(+)
 create mode 100644 drivers/clk/at91/clk-flexcom.c

-- 
1.8.2.2

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[PATCH v2 1/2] clk: at91: add a new compatible string for Flexcom in the DT documentation

[Cyrille Pitchen]

This patches documents the new bindings for the Flexcom clock, which will
be introduced by Atmel sama5d2x chips.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 .../devicetree/bindings/clock/at91-clock.txt         | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/at91-clock.txt b/Documentation/devicetree/bindings/clock/at91-clock.txt
index 7a4d492..df4f40b 100644
--- a/Documentation/devicetree/bindings/clock/at91-clock.txt
+++ b/Documentation/devicetree/bindings/clock/at91-clock.txt
@@ -77,6 +77,9 @@ Required properties:
 	"atmel,sama5d4-clk-h32mx":
 		at91 h32mx clock
 
+	"atmel,sama5d2-flexcom":
+		at91 flexcom clock
+
 Required properties for SCKC node:
 - reg : defines the IO memory reserved for the SCKC.
 - #size-cells : shall be 0 (reg is used to encode clk id).
@@ -461,3 +464,20 @@ For example:
 		compatible = "atmel,sama5d4-clk-h32mx";
 		clocks = <&mck>;
 	};
+
+Required properties for flexcom clock:
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the Flexcom peripheral clock from PMC.
+- reg : shall be the range for Flexcom dedicated I/O registers (without USART,
+  TWI or SPI registers).
+- atmel,flexcom-mode : shall be a string value among { "spi", "usart", "i2c",
+  "twi" }. "i2c" and "twi" are synonymous.
+
+For example:
+	flx0: flexcom@f8034000 {
+		compatible = "atmel,sama5d2-flexcom";
+		#clock-cells = <0>;
+		reg = <0xf8034000 0x200>;
+		clocks = <&flx0_clk>;
+		atmel,flexcom-mode = "spi";
+	};
-- 
1.8.2.2

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[PATCH v2 2/2] clk: at91: add Flexcom clock

[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 clock 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>
---
 arch/arm/mach-at91/Kconfig     |   3 +
 drivers/clk/at91/Makefile      |   1 +
 drivers/clk/at91/clk-flexcom.c | 160 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 164 insertions(+)
 create mode 100644 drivers/clk/at91/clk-flexcom.c

diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index fd95f34..8ce9b73 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -90,6 +90,9 @@ config HAVE_AT91_SMD
 config HAVE_AT91_H32MX
 	bool
 
+config HAVE_AT91_FLEXCOM
+	bool
+
 config SOC_SAM_V4_V5
 	bool
 
diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index 89a48a7..74711b8 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_HAVE_AT91_UTMI)		+= clk-utmi.o
 obj-$(CONFIG_HAVE_AT91_USB_CLK)		+= clk-usb.o
 obj-$(CONFIG_HAVE_AT91_SMD)		+= clk-smd.o
 obj-$(CONFIG_HAVE_AT91_H32MX)		+= clk-h32mx.o
+obj-$(CONFIG_HAVE_AT91_FLEXCOM)		+= clk-flexcom.o
diff --git a/drivers/clk/at91/clk-flexcom.c b/drivers/clk/at91/clk-flexcom.c
new file mode 100644
index 0000000..ce39093
--- /dev/null
+++ b/drivers/clk/at91/clk-flexcom.c
@@ -0,0 +1,160 @@
+/*
+ * Driver for Atmel AT91 Flexcom
+ *
+ * Copyright (C) 2014 Atmel Corporation
+ *
+ * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
+ *
+ * Based on drivers/clk/clk-axi-clkgen.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.
+ *
+ */
+
+#include <linux/platform_device.h>
+#include <linux/clk-provider.h>
+#include <linux/of.h>
+#include <linux/module.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
+
+struct clk_flexcom {
+	struct clk_hw	hw;
+	struct device	*dev;
+	u8 __iomem	*base;
+	u32		mr;
+	bool		show_once;
+};
+
+#define to_clk_flexcom(_hw)	container_of(_hw, struct clk_flexcom, hw)
+
+
+static int at91_flexcom_enable(struct clk_hw *hw)
+{
+	struct clk_flexcom *dev = to_clk_flexcom(hw);
+	u32 version;
+
+	if (!dev->show_once) {
+		dev->show_once = true;
+		version = __raw_readl(dev->base + FX_VERSION);
+		dev_info(dev->dev, "version: %#x\n", version);
+	}
+
+	__raw_writel(dev->mr, dev->base + FX_MR);
+	return 0;
+}
+
+static void at91_flexcom_disable(struct clk_hw *hw)
+{
+	struct clk_flexcom *dev = to_clk_flexcom(hw);
+
+	__raw_writel(FX_MR_NO_COM, dev->base + FX_MR);
+}
+
+static const struct clk_ops at91_flexcom_ops = {
+	.enable = at91_flexcom_enable,
+	.disable = at91_flexcom_disable,
+};
+
+static int at91_flexcom_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct clk_flexcom *dev;
+	struct resource *mem;
+	const char *parent_name, *clk_name, *mode;
+	struct clk *clk;
+	struct clk_init_data init;
+	u32 mr = FX_MR_NO_COM;
+	int err;
+
+	if (!np)
+		return -ENODEV;
+
+	err = of_property_read_string(np, "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;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dev->base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(dev->base))
+		return PTR_ERR(dev->base);
+
+	parent_name = of_clk_get_parent_name(np, 0);
+	if (!parent_name)
+		return -EINVAL;
+
+	clk_name = np->name;
+	of_property_read_string(np, "clock-output-names", &clk_name);
+
+	init.name = clk_name;
+	init.ops = &at91_flexcom_ops;
+	init.flags = 0;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	dev->hw.init = &init;
+	dev->dev = &pdev->dev;
+	dev->mr = mr;
+	platform_set_drvdata(pdev, dev);
+
+	clk = devm_clk_register(&pdev->dev, &dev->hw);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	return of_clk_add_provider(np, of_clk_src_simple_get, clk);
+}
+
+static int at91_flexcom_remove(struct platform_device *pdev)
+{
+	of_clk_del_provider(pdev->dev.of_node);
+
+	return 0;
+}
+
+static const struct of_device_id at91_flexcom_dt_ids[] = {
+	{ .compatible = "atmel,sama5d2-flexcom" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, at91_flexcom_dt_ids);
+
+static struct platform_driver at91_flexcom_driver = {
+	.driver		= {
+		.name	= "at91_flexcom",
+		.of_match_table = of_match_ptr(at91_flexcom_dt_ids),
+	},
+	.probe		= at91_flexcom_probe,
+	.remove		= at91_flexcom_remove,
+};
+module_platform_driver(at91_flexcom_driver);
+
+MODULE_ALIAS("platform:at91_flexcom");
+MODULE_DESCRIPTION("Atmel AT91 Flexcom driver");
+MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
+MODULE_LICENSE("GPL v2");
+
-- 
1.8.2.2

Re: [PATCH v2 2/2] clk: at91: add Flexcom clock

[Boris Brezillon]

Hi Cyrille,

On Tue, 2 Jun 2015 18:57:19 +0200
Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> 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 clock so the
> implementation is seamless for the existing Atmel SPI, I2C and USART drivers.

Could detail a bit more why you chose to represent this flexcom IP as
a clock device ?

I don't like to use this 'DT should represent real hardware' argument,
but to me, it looks like you're trying to use a false hardware
representation to avoid changing the peripheral drivers code, which is
wrong since the DT is supposed to represent the hardware blocks.

How about representing the flexcom as an MFD instead ?

Best Regards,

Boris


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Embedded Linux and Kernel engineering
http://free-electrons.com
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Re: [PATCH v2 2/2] clk: at91: add Flexcom clock

[Alexandre Belloni]

On 02/06/2015 at 19:04:35 +0200, Boris Brezillon wrote :
> Hi Cyrille,
> 
> On Tue, 2 Jun 2015 18:57:19 +0200
> Cyrille Pitchen <cyrille.pitchen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> 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 clock so the
> > implementation is seamless for the existing Atmel SPI, I2C and USART drivers.
> 
> Could detail a bit more why you chose to represent this flexcom IP as
> a clock device ?
> 
> I don't like to use this 'DT should represent real hardware' argument,
> but to me, it looks like you're trying to use a false hardware
> representation to avoid changing the peripheral drivers code, which is
> wrong since the DT is supposed to represent the hardware blocks.
> 
> How about representing the flexcom as an MFD instead ?
> 

It should probably be represented as an MFD. The MFD driver will parse
the chosen configuration and the probe the correct driver. You can have
a look at the recent ST LPC driver from Lee.


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Embedded Linux, Kernel and Android engineering
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