[PATCH v4 0/5] bcm2835: auxiliar device support for spi

[PATCH v4 0/5] bcm2835: auxiliar device support for spi

[kernel-TqfNSX0MhmxHKSADF0wUEw]

From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>

The BCM2835 contains 3 auxiliar devices:
* spi1
* spi2
* uart1

All of those 3 devices are enabled/disabled via a shared register,
which is set by default to be disabled.

Access to this register needs to get serialized.

So fter several iterations of discussions with the following idea:
* syscon - device tree should describe HW not drivers to use -
           'compatiblity = "brcm,bcm2835-aux-enable", "syscon";'
           is not acceptable
* regulator - it is not necessarily a regulator or a power gate
              that is implemented in HW, so it is not valid to use
              this framework

The recommendation was made to create a new minimal API in soc
just for access to this shared enable/disable register.

This patch-series implements:
* the bcm2835-auxiliar device enable/disable api in soc.
* the bcm2835-auxiliar spi device driver

The uart1 device driver (ns16550 based) is not implemented so far
but should be using the same API.

Martin Sperl (5):
  soc: bcm2835: auxiliar devices enable infrastructure
  ARM: bcm2835: add DT for the bcm2835 auxiliar devices
  dt/bindings: bcm2835: add binding documentation for bcm2835-aux
  spi: bcm2835: new driver implementing auxiliar spi1/spi2 on the
    bcm2835 soc
  dt/bindings: bcm2835: Add binding documentation for auxiliar spi
    devices

 .../bindings/soc/bcm/brcm,bcm2835-aux.txt          |   27 ++
 .../bindings/spi/brcm,bcm2835-aux-spi.txt          |   61 +++
 arch/arm/boot/dts/bcm2835.dtsi                     |   37 ++
 arch/arm/configs/bcm2835_defconfig                 |    1 +
 drivers/soc/Kconfig                                |    1 +
 drivers/soc/Makefile                               |    1 +
 drivers/soc/bcm/Kconfig                            |   11 +
 drivers/soc/bcm/Makefile                           |    1 +
 drivers/soc/bcm/bcm2835-aux.c                      |  154 ++++++
 drivers/spi/Kconfig                                |   12 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-bcm2835aux.c                       |  506 ++++++++++++++++++++
 include/linux/soc/bcm/bcm2835-aux.h                |   23 +
 13 files changed, 836 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt
 create mode 100644 Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt
 create mode 100644 drivers/soc/bcm/Kconfig
 create mode 100644 drivers/soc/bcm/Makefile
 create mode 100644 drivers/soc/bcm/bcm2835-aux.c
 create mode 100644 drivers/spi/spi-bcm2835aux.c
 create mode 100644 include/linux/soc/bcm/bcm2835-aux.h

--
1.7.10.4

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[PATCH v4 1/5] soc: bcm2835: auxiliar devices enable infrastructure

[kernel]

From: Martin Sperl <kernel@martin.sperl.org>

The bcm2835 SOC contains 3 auxiliar devices (spi1, spi2 and uart1)
that all are enabled via a shared register.

To serialize access to this shared register this soc-driver
is created that implements:
  bcm2835aux_enable(struct device *dev, const char *property);
  bcm2835aux_disable(struct device *dev, const char *property);

Which will read the property from the device tree of the device
and enable/disable that specific device as per device tree.

First use of this api will be spi-bcm2835aux.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
---
 drivers/soc/Kconfig                 |    1 +
 drivers/soc/Makefile                |    1 +
 drivers/soc/bcm/Kconfig             |   11 +++
 drivers/soc/bcm/Makefile            |    1 +
 drivers/soc/bcm/bcm2835-aux.c       |  154 +++++++++++++++++++++++++++++++++++
 include/linux/soc/bcm/bcm2835-aux.h |   23 ++++++
 6 files changed, 191 insertions(+)
 create mode 100644 drivers/soc/bcm/Kconfig
 create mode 100644 drivers/soc/bcm/Makefile
 create mode 100644 drivers/soc/bcm/bcm2835-aux.c
 create mode 100644 include/linux/soc/bcm/bcm2835-aux.h

diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
index 96ddecb..5506e39 100644
--- a/drivers/soc/Kconfig
+++ b/drivers/soc/Kconfig
@@ -1,5 +1,6 @@
 menu "SOC (System On Chip) specific Drivers"

+source "drivers/soc/bcm/Kconfig"
 source "drivers/soc/mediatek/Kconfig"
 source "drivers/soc/qcom/Kconfig"
 source "drivers/soc/sunxi/Kconfig"
diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
index 7dc7c0d..c5744e1 100644
--- a/drivers/soc/Makefile
+++ b/drivers/soc/Makefile
@@ -2,6 +2,7 @@
 # Makefile for the Linux Kernel SOC specific device drivers.
 #

+obj-$(CONFIG_ARCH_BCM)		+= bcm/
 obj-$(CONFIG_ARCH_MEDIATEK)	+= mediatek/
 obj-$(CONFIG_ARCH_QCOM)		+= qcom/
 obj-$(CONFIG_ARCH_SUNXI)	+= sunxi/
diff --git a/drivers/soc/bcm/Kconfig b/drivers/soc/bcm/Kconfig
new file mode 100644
index 0000000..b0af34b3
--- /dev/null
+++ b/drivers/soc/bcm/Kconfig
@@ -0,0 +1,11 @@
+#
+# Broadcom SoC drivers
+#
+config SOC_BCM2835_AUX
+	tristate "Broadcom BCM2835 aux"
+	depends on OF
+	depends on ARCH_BCM2835 || COMPILE_TEST
+
+	help
+	  Support to enable/disable the BCM2835 auxiliar
+	  devices spi1, spi2, uart1
diff --git a/drivers/soc/bcm/Makefile b/drivers/soc/bcm/Makefile
new file mode 100644
index 0000000..370a872
--- /dev/null
+++ b/drivers/soc/bcm/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SOC_BCM2835_AUX) += bcm2835-aux.o
diff --git a/drivers/soc/bcm/bcm2835-aux.c b/drivers/soc/bcm/bcm2835-aux.c
new file mode 100644
index 0000000..887508d
--- /dev/null
+++ b/drivers/soc/bcm/bcm2835-aux.c
@@ -0,0 +1,154 @@
+/*
+ * bcm2835-aux
+ *
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * Author: Martin Sperl <kernel@martin.sperl.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/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/soc/bcm/bcm2835-aux.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+static DEFINE_SPINLOCK(bcm2835aux_lock);
+
+static struct platform_driver bcm2835aux_driver;
+
+static int bcm2835aux_dev_match(struct device *dev, void *data)
+{
+	struct device_node *dn = data;
+
+	return (dev->of_node == dn) ? 1 : 0;
+}
+
+static void *bcm2835aux_find_base(struct device *dev, const char *property)
+{
+	struct device *found = NULL;
+	struct device_node *np;
+
+	/* get the phandle of the device */
+	np = of_parse_phandle(dev->of_node, property, 0);
+	if (!np) {
+		dev_err(dev, "missing property %s\n", property);
+		return ERR_PTR(-ENODEV);
+	}
+
+	/* now find the device it points to */
+	found = driver_find_device(&bcm2835aux_driver.driver, NULL,
+				   np, bcm2835aux_dev_match);
+	if (!found) {
+		dev_err(dev, "device for phandle of %s not found\n",
+			property);
+		return ERR_PTR(-ENODEV);
+	}
+
+	/* now we got the device, so return the pointer */
+	return dev_get_drvdata(found);
+}
+
+static u32 bcm2835aux_find_mask(struct device *dev, const char *property)
+{
+	int err;
+	u32 mask;
+
+	err = of_property_read_u32_index(dev->of_node, property, 1, &mask);
+	if (err) {
+		dev_err(dev, "missing argument to %s: %d\n",
+			property, err);
+		return 0;
+	}
+
+	return mask;
+}
+
+static int bcm2835aux_bitset(struct device *dev, const char *property,
+			     bool set)
+{
+	u32 v, mask;
+	unsigned long flags;
+	void __iomem *base;
+
+	/* find the device */
+	base = bcm2835aux_find_base(dev, property);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	/* and extract the mask */
+	mask = bcm2835aux_find_mask(dev, property);
+	if (!mask)
+		return -ENOENT;
+
+	spin_lock_irqsave(&bcm2835aux_lock, flags);
+
+	v = readl(base);
+	if (set)
+		v |= mask;
+	else
+		v &= ~mask;
+
+	writel(v, base);
+
+	spin_unlock_irqrestore(&bcm2835aux_lock, flags);
+
+	return 0;
+}
+
+int bcm2835aux_enable(struct device *dev, const char *property)
+{
+	return bcm2835aux_bitset(dev, property, true);
+}
+EXPORT_SYMBOL_GPL(bcm2835aux_enable);
+
+int bcm2835aux_disable(struct device *dev, const char *property)
+{
+	return bcm2835aux_bitset(dev, property, false);
+}
+EXPORT_SYMBOL_GPL(bcm2835aux_disable);
+
+static int bcm2835aux_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	void __iomem *base;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	platform_set_drvdata(pdev, base);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835aux_match[] = {
+	{ .compatible = "brcm,bcm2835-aux", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, bcm2835aux_match);
+
+static struct platform_driver bcm2835aux_driver = {
+	.driver = {
+		.name           = "bcm2835-aux",
+		.of_match_table	= bcm2835aux_match,
+	},
+	.probe			= bcm2835aux_probe,
+};
+module_platform_driver(bcm2835aux_driver);
+
+MODULE_DESCRIPTION("enable/disable driver for aux-spi1/spi2/uart1 on Broadcom BCM2835");
+MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/soc/bcm/bcm2835-aux.h b/include/linux/soc/bcm/bcm2835-aux.h
new file mode 100644
index 0000000..17a64c6
--- /dev/null
+++ b/include/linux/soc/bcm/bcm2835-aux.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __BCM2835_AUX_H__
+#define __BCM2835_AUX_H__
+
+struct device;
+
+int bcm2835aux_enable(struct device *dev, const char *property);
+int bcm2835aux_disable(struct device *dev, const char *property);
+
+#endif
--
1.7.10.4

Re: [PATCH v4 1/5] soc: bcm2835: auxiliar devices enable infrastructure

[Stephen Warren]

On 08/24/2015 02:40 AM, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
> From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
> 
> The bcm2835 SOC contains 3 auxiliar devices (spi1, spi2 and uart1)
> that all are enabled via a shared register.
> 
> To serialize access to this shared register this soc-driver
> is created that implements:
>   bcm2835aux_enable(struct device *dev, const char *property);
>   bcm2835aux_disable(struct device *dev, const char *property);
> 
> Which will read the property from the device tree of the device
> and enable/disable that specific device as per device tree.
> 
> First use of this api will be spi-bcm2835aux.

> diff --git a/drivers/soc/bcm/bcm2835-aux.c b/drivers/soc/bcm/bcm2835-aux.c

> +static void *bcm2835aux_find_base(struct device *dev, const char *property)
> +{
> +	struct device *found = NULL;
> +	struct device_node *np;
> +
> +	/* get the phandle of the device */
> +	np = of_parse_phandle(dev->of_node, property, 0);
> +	if (!np) {
> +		dev_err(dev, "missing property %s\n", property);
> +		return ERR_PTR(-ENODEV);
> +	}
> +
> +	/* now find the device it points to */
> +	found = driver_find_device(&bcm2835aux_driver.driver, NULL,
> +				   np, bcm2835aux_dev_match);
> +	if (!found) {
> +		dev_err(dev, "device for phandle of %s not found\n",
> +			property);
> +		return ERR_PTR(-ENODEV);

That should return ERR_PTR(-EPROBE_DEFER) so that client drivers know
when to defer their own probe, and not print an error. This is an
expected condition during probing. I could have sworn this was correct
in a previous patch revision.
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[PATCH v4 2/5] ARM: bcm2835: add DT for the bcm2835 auxiliar devices

[kernel]

From: Martin Sperl <kernel@martin.sperl.org>

Add device tree definitions for auxiliar bcm2835 devices:
* spi1
* spi2
* uart1

This also include a device to get used by the relevant
device-drivers (via a shared register) to enable/disable
the HW-block.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
---
 arch/arm/boot/dts/bcm2835.dtsi |   37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi
index 301c73f..4e6fc61 100644
--- a/arch/arm/boot/dts/bcm2835.dtsi
+++ b/arch/arm/boot/dts/bcm2835.dtsi
@@ -158,6 +158,43 @@
 		arm-pmu {
 			compatible = "arm,arm1176-pmu";
 		};
+
+		aux_enable: aux_enable@0x7e215004 {
+			compatible = "brcm,bcm2835-aux";
+			reg = <0x7e215004 0x04>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+		};
+
+		uart1: uart@7e215040 {
+			compatible = "brcm,bcm2835-aux-uart";
+			reg = <0x7e215040 0x40>;
+			interrupts = <1 29>;
+			brcm,aux-enable = <&aux_enable 1>;
+			status = "disabled";
+		};
+
+		spi1: spi@7e215080 {
+			compatible = "brcm,bcm2835-aux-spi";
+			reg = <0x7e215080 0x40>;
+			brcm,aux-enable = <&aux_enable 2>;
+			interrupts = <1 29>;
+			clocks = <&clk_spi>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "disabled";
+		};
+
+		spi2: spi@7e2150c0 {
+			compatible = "brcm,bcm2835-aux-spi";
+			reg = <0x7e2150c0 0x40>;
+			brcm,aux-enable = <&aux_enable 4>;
+			interrupts = <1 29>;
+			clocks = <&clk_spi>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "disabled";
+		};
 	};

 	clocks {
--
1.7.10.4

[PATCH v4 3/5] dt/bindings: bcm2835: add binding documentation for bcm2835-aux

[kernel]

From: Martin Sperl <kernel@martin.sperl.org>

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
---
 .../bindings/soc/bcm/brcm,bcm2835-aux.txt          |   27 ++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt

diff --git a/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt
new file mode 100644
index 0000000..8b79cf3
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt
@@ -0,0 +1,27 @@
+Broadcom BCM2835 auxiliar device enable register
+
+the BCM2835 contains 3 auxiliar devices (spi1/spi2/uart1)
+which need to get enabled via a shared register.
+
+Required properties:
+- compatible: Should be "brcm,bcm2835-aux".
+- reg: Should contain register location and length for the
+       enable register
+
+Example:
+
+aux_enable: aux_enable@0x7e215004 {
+	compatible = "bcrm,bcm2835-aux";
+	reg = <0x7e215004 0x04>;
+};
+
+Typically used in the respective auxiliar device descriptions
+like this:
+
+uart1: uart@7e215040 {
+	...
+	brcm,aux-enable = <&aux_enable 1>;
+	...
+};
+
+The name of the property can be device/driver specific.
--
1.7.10.4

Re: [PATCH v4 3/5] dt/bindings: bcm2835: add binding documentation for bcm2835-aux

[Stephen Warren]

On 08/24/2015 02:40 AM, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
> From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>

Patch description?

> diff --git a/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt

> +Required properties:
> +- compatible: Should be "brcm,bcm2835-aux".
> +- reg: Should contain register location and length for the
> +       enable register

As I mentioned before, why not all the aux registers (that aren't part
of a sub-device like SPI).

> +Example:
> +
> +aux_enable: aux_enable@0x7e215004 {
> +	compatible = "bcrm,bcm2835-aux";
> +	reg = <0x7e215004 0x04>;

I'd expect that to be <0x7e215000 0x8>;
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Re: [PATCH v4 3/5] dt/bindings: bcm2835: add binding documentation for bcm2835-aux

[Martin Sperl]

> On 26.08.2015, at 03:44, Stephen Warren <swarren@wwwdotorg.org> wrote:
> 
> On 08/24/2015 02:40 AM, kernel@martin.sperl.org wrote:
> 
>> +Example:
>> +
>> +aux_enable: aux_enable@0x7e215004 {
>> +	compatible = "bcrm,bcm2835-aux";
>> +	reg = <0x7e215004 0x04>;
> 
> I'd expect that to be <0x7e215000 0x8>;

The reason is that we just handle enable with this driver,
which just requires access to the 0x7e215004 register.

The 0x7e215000 register (interrupt mask) could be used by a
cascaded interrupt-controller, but as the spi and uart drivers
can run with shared interrupts this is not a necessity.

Martin

Re: [PATCH v4 3/5] dt/bindings: bcm2835: add binding documentation for bcm2835-aux

[Stephen Warren]

On 09/04/2015 01:26 AM, Martin Sperl wrote:
> 
>> On 26.08.2015, at 03:44, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote:
>>
>> On 08/24/2015 02:40 AM, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
>>
>>> +Example:
>>> +
>>> +aux_enable: aux_enable@0x7e215004 {
>>> +	compatible = "bcrm,bcm2835-aux";
>>> +	reg = <0x7e215004 0x04>;
>>
>> I'd expect that to be <0x7e215000 0x8>;
> 
> The reason is that we just handle enable with this driver,
> which just requires access to the 0x7e215004 register.
> 
> The 0x7e215000 register (interrupt mask) could be used by a
> cascaded interrupt-controller, but as the spi and uart drivers
> can run with shared interrupts this is not a necessity.

The DT is supposed to describe the HW, not any particular SW's use of
the HW. If the HW block has 2 registers, so must the DT reg property.

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Re: [PATCH v4 3/5] dt/bindings: bcm2835: add binding documentation for bcm2835-aux

[Martin Sperl]

> On 16.09.2015, at 06:12, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote:
> 
> On 09/04/2015 01:26 AM, Martin Sperl wrote:
>> 
>>> On 26.08.2015, at 03:44, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote:
>>> 
>>> On 08/24/2015 02:40 AM, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
>>> 
>>>> +Example:
>>>> +
>>>> +aux_enable: aux_enable@0x7e215004 {
>>>> +	compatible = "bcrm,bcm2835-aux";
>>>> +	reg = <0x7e215004 0x04>;
>>> 
>>> I'd expect that to be <0x7e215000 0x8>;
>> 
>> The reason is that we just handle enable with this driver,
>> which just requires access to the 0x7e215004 register.
>> 
>> The 0x7e215000 register (interrupt mask) could be used by a
>> cascaded interrupt-controller, but as the spi and uart drivers
>> can run with shared interrupts this is not a necessity.
> 
> The DT is supposed to describe the HW, not any particular SW's use of
> the HW. If the HW block has 2 registers, so must the DT reg property.

Please look at V6 of the patch-series, that uses Erics clock-patch.
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[PATCH v4 4/5] spi: bcm2835: new driver implementing auxiliar spi1/spi2 on the bcm2835 soc

[kernel]

From: Martin Sperl <kernel@martin.sperl.org>

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
---
 arch/arm/configs/bcm2835_defconfig |    1 +
 drivers/spi/Kconfig                |   12 +
 drivers/spi/Makefile               |    1 +
 drivers/spi/spi-bcm2835aux.c       |  506 ++++++++++++++++++++++++++++++++++++
 4 files changed, 520 insertions(+)
 create mode 100644 drivers/spi/spi-bcm2835aux.c

diff --git a/arch/arm/configs/bcm2835_defconfig b/arch/arm/configs/bcm2835_defconfig
index 31cb073..a205c8b 100644
--- a/arch/arm/configs/bcm2835_defconfig
+++ b/arch/arm/configs/bcm2835_defconfig
@@ -75,6 +75,7 @@ CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_BCM2835=y
 CONFIG_SPI=y
 CONFIG_SPI_BCM2835=y
+CONFIG_SPI_BCM2835AUX=y
 CONFIG_GPIO_SYSFS=y
 # CONFIG_HWMON is not set
 CONFIG_FB=y
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 43f6d3d..133f5ca 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -88,6 +88,18 @@ config SPI_BCM2835
 	  is for the regular SPI controller. Slave mode operation is not also
 	  not supported.

+config SPI_BCM2835AUX
+	tristate "BCM2835 SPI auxiliar controller"
+	depends on ARCH_BCM2835 || COMPILE_TEST
+	depends on GPIOLIB
+	select SOC_BCM2835AUX
+	help
+	  This selects a driver for the Broadcom BCM2835 SPI aux master.
+
+	  The BCM2835 contains two types of SPI master controller; the
+	  "universal SPI master", and the regular SPI controller.
+	  This driver is for the universal/auxiliar SPI controller.
+
 config SPI_BFIN5XX
 	tristate "SPI controller driver for ADI Blackfin5xx"
 	depends on BLACKFIN && !BF60x
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 9746beb2..4e9cba3 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_SPI_ATMEL)			+= spi-atmel.o
 obj-$(CONFIG_SPI_ATH79)			+= spi-ath79.o
 obj-$(CONFIG_SPI_AU1550)		+= spi-au1550.o
 obj-$(CONFIG_SPI_BCM2835)		+= spi-bcm2835.o
+obj-$(CONFIG_SPI_BCM2835AUX)		+= spi-bcm2835aux.o
 obj-$(CONFIG_SPI_BCM53XX)		+= spi-bcm53xx.o
 obj-$(CONFIG_SPI_BCM63XX)		+= spi-bcm63xx.o
 obj-$(CONFIG_SPI_BCM63XX_HSSPI)		+= spi-bcm63xx-hsspi.o
diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
new file mode 100644
index 0000000..9e056f6
--- /dev/null
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -0,0 +1,506 @@
+/*
+ * Driver for Broadcom BCM2835 SPI Controllers
+ *
+ * the driver does not rely on the native chipselects at all
+ * but only uses the gpio type chipselects
+ *
+ * Based on: spi-bcm2835.c
+ *
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * 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 program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/soc/bcm/bcm2835-aux.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/spinlock.h>
+
+/*
+ * shared aux registers between spi1/spi2 and uart1
+ *
+ * these defines could go to a separate module if needed
+ * so that it can also get used with the uart1 implementation
+ * when it materializes.
+ */
+
+/* the AUX register offsets */
+#define BCM2835_AUX_IRQ		0x00
+#define BCM2835_AUX_ENABLE	0x04
+
+/* the AUX Bitfield identical for both register */
+#define BCM2835_AUX_BIT_UART	0x00000001
+#define BCM2835_AUX_BIT_SPI1	0x00000002
+#define BCM2835_AUX_BIT_SPI2	0x00000004
+
+/*
+ * spi register defines
+ *
+ * note there is garbage in the "official" documentation,
+ * so somedata taken from the file:
+ *   brcm_usrlib/dag/vmcsx/vcinclude/bcm2708_chip/aux_io.h
+ * inside of:
+ *   http://www.broadcom.com/docs/support/videocore/Brcm_Android_ICS_Graphics_Stack.tar.gz
+ */
+
+/* SPI register offsets */
+#define BCM2835_AUX_SPI_CNTL0	0x00
+#define BCM2835_AUX_SPI_CNTL1	0x04
+#define BCM2835_AUX_SPI_STAT	0x08
+#define BCM2835_AUX_SPI_PEEK	0x0C
+#define BCM2835_AUX_SPI_IO	0x20
+#define BCM2835_AUX_SPI_TXHOLD	0x30
+
+/* Bitfields in CNTL0 */
+#define BCM2835_AUX_SPI_CNTL0_SPEED	0xFFF00000
+#define BCM2835_AUX_SPI_CNTL0_SPEED_MAX	0xFFF
+#define BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT	20
+#define BCM2835_AUX_SPI_CNTL0_CS	0x000E0000
+#define BCM2835_AUX_SPI_CNTL0_POSTINPUT	0x00010000
+#define BCM2835_AUX_SPI_CNTL0_VAR_CS	0x00008000
+#define BCM2835_AUX_SPI_CNTL0_VAR_WIDTH	0x00004000
+#define BCM2835_AUX_SPI_CNTL0_DOUTHOLD	0x00003000
+#define BCM2835_AUX_SPI_CNTL0_ENABLE	0x00000800
+#define BCM2835_AUX_SPI_CNTL0_CPHA_IN	0x00000400
+#define BCM2835_AUX_SPI_CNTL0_CLEARFIFO	0x00000200
+#define BCM2835_AUX_SPI_CNTL0_CPHA_OUT	0x00000100
+#define BCM2835_AUX_SPI_CNTL0_CPOL	0x00000080
+#define BCM2835_AUX_SPI_CNTL0_MSBF_OUT	0x00000040
+#define BCM2835_AUX_SPI_CNTL0_SHIFTLEN	0x0000003F
+
+/* Bitfields in CNTL1 */
+#define BCM2835_AUX_SPI_CNTL1_CSHIGH	0x00000700
+#define BCM2835_AUX_SPI_CNTL1_IDLE	0x00000080
+#define BCM2835_AUX_SPI_CNTL1_TXEMPTY	0x00000040
+#define BCM2835_AUX_SPI_CNTL1_MSBF_IN	0x00000002
+#define BCM2835_AUX_SPI_CNTL1_KEEP_IN	0x00000001
+
+/* Bitfields in STAT */
+#define BCM2835_AUX_SPI_STAT_TX_LVL	0xFF000000
+#define BCM2835_AUX_SPI_STAT_RX_LVL	0x00FF0000
+#define BCM2835_AUX_SPI_STAT_TX_FULL	0x00000400
+#define BCM2835_AUX_SPI_STAT_TX_EMPTY	0x00000200
+#define BCM2835_AUX_SPI_STAT_RX_FULL	0x00000100
+#define BCM2835_AUX_SPI_STAT_RX_EMPTY	0x00000080
+#define BCM2835_AUX_SPI_STAT_BUSY	0x00000040
+#define BCM2835_AUX_SPI_STAT_BITCOUNT	0x0000003F
+
+/* timeout values */
+#define BCM2835_AUX_SPI_POLLING_LIMIT_US	30
+#define BCM2835_AUX_SPI_POLLING_JIFFIES		2
+
+#define BCM2835_AUX_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
+				  | SPI_NO_CS)
+
+#define DRV_NAME	"spi-bcm2835aux"
+#define ENABLE_PROPERTY "brcm,aux-enable"
+
+struct bcm2835aux_spi {
+	void __iomem *regs;
+	struct clk *clk;
+	int irq;
+	u32 cntl[2];
+	const u8 *tx_buf;
+	u8 *rx_buf;
+	int tx_len;
+	int rx_len;
+};
+
+static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned reg)
+{
+	return readl(bs->regs + reg);
+}
+
+static inline void bcm2835aux_wr(struct bcm2835aux_spi *bs, unsigned reg,
+				 u32 val)
+{
+	writel(val, bs->regs + reg);
+}
+
+static inline void bcm2835aux_rd_fifo(struct bcm2835aux_spi *bs)
+{
+	u32 data;
+	int i;
+	int count = min(bs->rx_len, 3);
+
+	data = bcm2835aux_rd(bs, BCM2835_AUX_SPI_IO);
+	if (bs->rx_buf) {
+		for (i = 0; i < count; i++)
+			*bs->rx_buf++ = (data >> (8 * (2 - i))) & 0xff;
+	}
+	bs->rx_len -= count;
+}
+
+static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs)
+{
+	u32 data;
+	u8 byte;
+	int count;
+	int i;
+
+	/* gather up to 3 bytes to write to the FIFO */
+	count = min(bs->tx_len, 3);
+	data = 0;
+	for (i = 0; i < count; i++) {
+		byte = bs->tx_buf ? *bs->tx_buf++ : 0;
+		data |= byte << (8 * (2 - i));
+	}
+
+	/* and set the variable bit-length */
+	data |= (count * 8) << 24;
+
+	/* and decrement length */
+	bs->tx_len -= count;
+
+	/* write to the correct TX-register */
+	if (bs->tx_len)
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_TXHOLD, data);
+	else
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_IO, data);
+}
+
+static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs)
+{
+	/* disable spi clearing fifo and interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, 0);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0,
+		      BCM2835_AUX_SPI_CNTL0_CLEARFIFO);
+}
+
+static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	irqreturn_t ret = IRQ_NONE;
+
+	/* check if we have data to read */
+	while (bs->rx_len &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_RX_EMPTY))) {
+		bcm2835aux_rd_fifo(bs);
+		ret = IRQ_HANDLED;
+	}
+
+	/* check if we have data to write */
+	while (bs->tx_len &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
+		bcm2835aux_wr_fifo(bs);
+		ret = IRQ_HANDLED;
+	}
+
+	/* and check if we have reached "done" */
+	while (bs->rx_len &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_BUSY))) {
+		bcm2835aux_rd_fifo(bs);
+		ret = IRQ_HANDLED;
+	}
+
+	/* and if rx_len is 0 then wake up completion and disable spi */
+	if (!bs->rx_len) {
+		bcm2835aux_spi_reset_hw(bs);
+		complete(&master->xfer_completion);
+	}
+
+	/* and return */
+	return ret;
+}
+
+static int __bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
+					     struct spi_device *spi,
+					     struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* enable interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1] |
+		BCM2835_AUX_SPI_CNTL1_TXEMPTY |
+		BCM2835_AUX_SPI_CNTL1_IDLE);
+
+	/* and wait for finish... */
+	return 1;
+}
+
+static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
+					   struct spi_device *spi,
+					   struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* fill in registers and fifos before enabling interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	/* fill in tx fifo with data before enabling interrupts */
+	while ((bs->tx_len) &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
+		bcm2835aux_wr_fifo(bs);
+	}
+
+	/* now run the interrupt mode */
+	return __bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
+}
+
+static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
+					    struct spi_device *spi,
+					    struct spi_transfer *tfr,
+					    unsigned long xfer_time_us)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	unsigned long timeout;
+	u32 stat;
+
+	/* configure spi */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	/* set the timeout */
+	timeout = jiffies + BCM2835_AUX_SPI_POLLING_JIFFIES;
+
+	/* loop until finished the transfer */
+	while (bs->rx_len) {
+		/* read status */
+		stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT);
+
+		/* fill in tx fifo with remaining data */
+		if ((bs->tx_len) && (!(stat & BCM2835_AUX_SPI_STAT_TX_FULL))) {
+			bcm2835aux_wr_fifo(bs);
+			continue;
+		}
+
+		/* read data from fifo for both cases */
+		if (!(stat & BCM2835_AUX_SPI_STAT_RX_EMPTY)) {
+			bcm2835aux_rd_fifo(bs);
+			continue;
+		}
+		if (!(stat & BCM2835_AUX_SPI_STAT_BUSY)) {
+			bcm2835aux_rd_fifo(bs);
+			continue;
+		}
+
+		/* there is still data pending to read check the timeout */
+		if (bs->rx_len && time_after(jiffies, timeout)) {
+			dev_dbg_ratelimited(&spi->dev,
+					    "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
+					    jiffies - timeout,
+					    bs->tx_len, bs->rx_len);
+			/* forward to interrupt handler */
+			return __bcm2835aux_spi_transfer_one_irq(master,
+							       spi, tfr);
+		}
+	}
+
+	/* Transfer complete - reset SPI HW */
+	bcm2835aux_spi_reset_hw(bs);
+
+	/* and return without waiting for completion */
+	return 0;
+}
+
+static int bcm2835aux_spi_transfer_one(struct spi_master *master,
+				       struct spi_device *spi,
+				       struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	unsigned long spi_hz, clk_hz, speed;
+	unsigned long spi_used_hz, xfer_time_us;
+
+	/* calculate the registers to handle
+	 *
+	 * note that we use the variable data mode, which
+	 * is not optimal for longer transfers as we waste registers
+	 * resulting (potentially) in more interrupts when transferring
+	 * more than 12 bytes
+	 */
+	bs->cntl[0] = BCM2835_AUX_SPI_CNTL0_ENABLE |
+		      BCM2835_AUX_SPI_CNTL0_VAR_WIDTH |
+		      BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
+	bs->cntl[1] = BCM2835_AUX_SPI_CNTL1_MSBF_IN;
+
+	/* set clock */
+	spi_hz = tfr->speed_hz;
+	clk_hz = clk_get_rate(bs->clk);
+
+	if (spi_hz >= clk_hz / 2) {
+		speed = 0;
+	} else if (spi_hz) {
+		speed = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1;
+		if (speed >  BCM2835_AUX_SPI_CNTL0_SPEED_MAX)
+			speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
+	} else { /* the slowest we can go */
+		speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
+	}
+	bs->cntl[0] |= speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT;
+	spi_used_hz = clk_hz / (2 * (speed + 1));
+
+	/* handle all the modes */
+	if (spi->mode & SPI_CPOL)
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPOL;
+	if (spi->mode & SPI_CPHA)
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPHA_OUT |
+			       BCM2835_AUX_SPI_CNTL0_CPHA_IN;
+
+	/* set transmit buffers and length */
+	bs->tx_buf = tfr->tx_buf;
+	bs->rx_buf = tfr->rx_buf;
+	bs->tx_len = tfr->len;
+	bs->rx_len = tfr->len;
+
+	/* calculate the estimated time in us the transfer runs */
+	xfer_time_us = tfr->len
+		* 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */
+		* 1000000 / spi_used_hz;
+
+	/* run in polling mode for short transfers */
+	if (xfer_time_us < BCM2835_AUX_SPI_POLLING_LIMIT_US)
+		return bcm2835aux_spi_transfer_one_poll(master, spi, tfr,
+							xfer_time_us);
+
+	/* run in interrupt mode for all others */
+	return bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
+}
+
+static void bcm2835aux_spi_handle_err(struct spi_master *master,
+				      struct spi_message *msg)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	bcm2835aux_spi_reset_hw(bs);
+}
+
+static int bcm2835aux_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct bcm2835aux_spi *bs;
+	struct resource *res;
+	int err;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*bs));
+	if (!master) {
+		dev_err(&pdev->dev, "spi_alloc_master() failed\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, master);
+	master->mode_bits = BCM2835_AUX_SPI_MODE_BITS;
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	master->num_chipselect = -1;
+	master->transfer_one = bcm2835aux_spi_transfer_one;
+	master->handle_err = bcm2835aux_spi_handle_err;
+	master->dev.of_node = pdev->dev.of_node;
+
+	bs = spi_master_get_devdata(master);
+
+	/* the main area */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bs->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(bs->regs)) {
+		err = PTR_ERR(bs->regs);
+		goto out_master_put;
+	}
+
+	bs->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(bs->clk)) {
+		err = PTR_ERR(bs->clk);
+		dev_err(&pdev->dev, "could not get clk: %d\n", err);
+		goto out_master_put;
+	}
+	bs->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+	if (bs->irq <= 0) {
+		dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
+		err = bs->irq ? bs->irq : -ENODEV;
+		goto out_master_put;
+	}
+
+	clk_prepare_enable(bs->clk);
+
+	err = devm_request_irq(&pdev->dev, bs->irq,
+			       bcm2835aux_spi_interrupt,
+			       IRQF_SHARED,
+			       dev_name(&pdev->dev), master);
+	if (err) {
+		dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
+		goto out_clk_disable;
+	}
+
+	/* enable HW block */
+	bcm2835aux_enable(&pdev->dev, ENABLE_PROPERTY);
+
+	/* reset SPI-HW block */
+	bcm2835aux_spi_reset_hw(bs);
+
+	err = devm_spi_register_master(&pdev->dev, master);
+	if (err) {
+		dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
+		goto out_hw_disable;
+	}
+
+	return 0;
+
+out_hw_disable:
+	bcm2835aux_disable(&pdev->dev, ENABLE_PROPERTY);
+out_clk_disable:
+	clk_disable_unprepare(bs->clk);
+out_master_put:
+	spi_master_put(master);
+	return err;
+}
+
+static int bcm2835aux_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* Clear FIFOs, and disable the HW block */
+	clk_disable_unprepare(bs->clk);
+
+	bcm2835aux_spi_reset_hw(bs);
+
+	/* disable HW block */
+	bcm2835aux_disable(&pdev->dev, ENABLE_PROPERTY);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835aux_spi_match[] = {
+	{ .compatible = "brcm,bcm2835-aux-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, bcm2835aux_spi_match);
+
+static struct platform_driver bcm2835aux_spi_driver = {
+	.driver		= {
+		.name		= DRV_NAME,
+		.of_match_table	= bcm2835aux_spi_match,
+	},
+	.probe		= bcm2835aux_spi_probe,
+	.remove		= bcm2835aux_spi_remove,
+};
+module_platform_driver(bcm2835aux_spi_driver);
+
+MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835 aux");
+MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
+MODULE_LICENSE("GPL v2");
--
1.7.10.4

Re: [PATCH v4 4/5] spi: bcm2835: new driver implementing auxiliar spi1/spi2 on the bcm2835 soc

[Stephen Warren]

On 08/24/2015 02:40 AM, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
> From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>

Patch description?

>  arch/arm/configs/bcm2835_defconfig |    1 +
>  drivers/spi/Kconfig                |   12 +
>  drivers/spi/Makefile               |    1 +
>  drivers/spi/spi-bcm2835aux.c       |  506 ++++++++++++++++++++++++++++++++++++

A change to the defconfig would be applied by the RPi maintainers, and a
change to drivers/spi by the SPI maintainers. Those need to be in
different patches.

> diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c

> +static int bcm2835aux_spi_probe(struct platform_device *pdev)

> +	clk_prepare_enable(bs->clk);

Error checking?

> +	/* enable HW block */
> +	bcm2835aux_enable(&pdev->dev, ENABLE_PROPERTY);

The return value needs to be error-checked, so that deferred probe can
work, and so other kinds of errors can be detected. Wasn't this correct
in a previous patch version?

Note that I didn't review any code besides probe(), remove() and the
driver boiler-plate that refers to those functions.

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[PATCH v4 5/5] dt/bindings: bcm2835: Add binding documentation for auxiliar spi devices

[kernel-TqfNSX0MhmxHKSADF0wUEw]

From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>

Signed-off-by: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
---
 .../bindings/spi/brcm,bcm2835-aux-spi.txt          |   61 ++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt

diff --git a/Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt b/Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt
new file mode 100644
index 0000000..2a69a3b
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt
@@ -0,1 +1,61 @@
+Broadcom BCM2835 auxiliar SPI1/2 controller
+
+The BCM2835 contains two forms of SPI master controller, one known simply as
+SPI0, and the other known as the "Universal SPI Master"; part of the
+auxiliary block. This binding applies to the SPI1/2 controller.
+
+Required properties:
+- compatible: Should be "brcm,bcm2835-aux-spi".
+- reg: Should contain register location and length for the spi block
+       as well as for the common aux block control
+- interrupts: Should contain shared interrupt of the aux block
+- clocks: The clock feeding the SPI controller.
+- cs-gpios: the cs-gpios (native cs is NOT supported)
+	    see also spi-bus.txt
+- bcrm,aux-enable: the bcrm,bcm2835-aux-enable config entry to handle
+		  enabling/disabling of the spi1/spi2/uart1 HW block
+		  second "argument" is the mask to apply to the
+		  enable register
+
+Example:
+
+spi1@7e215080 {
+	compatible = "brcm,bcm2835-aux-spi";
+	reg = <0x7e215080 0x40>;
+	interrupts = <1 29>;
+	clocks = <&clk_spi>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	cs-gpios = <&gpio 18>, <&gpio 17>, <&gpio 16>;
+	bcrm,aux-enable = <&aux_enable 2>;
+};
+
+spi2@7e2150c0 {
+	compatible = "brcm,bcm2835-aux-spi";
+	reg = <0x7e2150c0 0x40>;
+	interrupts = <1 29>;
+	clocks = <&clk_spi>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	cs-gpios = <&gpio 43>, <&gpio 44>, <&gpio 45>;
+	bcrm,aux-enable = <&aux_enable 4>;
+};
+
+/* the necessary syscon config referenced above*/
+aux_enable: aux_enable@0x7e215004 {
+	compatible = "bcrm,bcm2835-aux";
+	reg = <0x7e215004 0x04>;
+};
+
+Note that it also requires the GPIOs to be set up with the
+correct ALT-functions.
+
+For spi1 the following pins need to be set as:
+* ALT4: 19, 20, 21 (MISO, MOSI, SCK)
+
+For spi2 the following pins need to be set as:
+* ALT4: 40, 41, 42 (MISO, MOSI, SCK)
+
+CS-GPIOS need to get set as output - typically:
+* spi1: 18, 17, 16 (CS0, CS1, CS2)
+* spi2: 43, 44, 45 (CS0, CS1, CS2)
--
1.7.10.4

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Re: [PATCH v4 5/5] dt/bindings: bcm2835: Add binding documentation for auxiliar spi devices

[Stephen Warren]

On 08/24/2015 02:40 AM, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
> From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>

Patch description?

> diff --git a/Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt b/Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt

> +Required properties:
> +- compatible: Should be "brcm,bcm2835-aux-spi".
> +- reg: Should contain register location and length for the spi block
> +       as well as for the common aux block control

Is that meant to imply that reg should contain a single value that
covers both the common aux registers and the SPI device, or two separate
values, one for the aux common registers and another for the SPI device?
Neither of those options sound correct. I would expect only a single
entry which covered solely the SPI registers. The common aux registers
are owned by the other brcm,bcm2835-aux binding.

> +Example:
> +
> +spi1@7e215080 {
> +	compatible = "brcm,bcm2835-aux-spi";
> +	reg = <0x7e215080 0x40>;

That seems to match what I'd expect, but doesn't correspond to the
description above.

> +/* the necessary syscon config referenced above*/
> +aux_enable: aux_enable@0x7e215004 {

It's not a "syscon"...

> +Note that it also requires the GPIOs to be set up with the
> +correct ALT-functions.
> +
> +For spi1 the following pins need to be set as:
> +* ALT4: 19, 20, 21 (MISO, MOSI, SCK)
> +
> +For spi2 the following pins need to be set as:
> +* ALT4: 40, 41, 42 (MISO, MOSI, SCK)
> +
> +CS-GPIOS need to get set as output - typically:
> +* spi1: 18, 17, 16 (CS0, CS1, CS2)
> +* spi2: 43, 44, 45 (CS0, CS1, CS2)

That's generally true of any HW block, and has nothing to do with the
binding for the device. I would suggest removing that chunk of text.

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