[RFC PATCH] soc: bcm2835: auxiliar devices enable infrastructure
kernel at martin.sperl.org
kernel at martin.sperl.org
Tue Aug 4 01:41:57 PDT 2015
From: Martin Sperl <kernel at 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 this soc-driver is created that implements
bcm2835aux_enable(struct device *dev, const char *property);
bcm2835aux_disable(struct device *dev, const char *property);
Ehich 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, which will
set the following property in the device tree for the devices:
brcm,aux-enable = <&aux_enable 4>;
And call:
bcm2835aux_enable(&spi->dev, "brcm,aux-enable");
This allows to define different property names based on the
driver.
Signed-off-by: Martin Sperl <kernel at martin.sperl.org>
---
.../bindings/soc/bcm/brcm,bcm2835-aux.txt | 16 ++
drivers/soc/Kconfig | 1 +
drivers/soc/Makefile | 1 +
drivers/soc/bcm/Kconfig | 10 ++
drivers/soc/bcm/Makefile | 1 +
drivers/soc/bcm/bcm2835-aux.c | 155 ++++++++++++++++++++
include/linux/soc/bcm/bcm2835-aux.h | 24 +++
7 files changed, 208 insertions(+)
create mode 100644 Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.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 include/linux/soc/bcm/bcm2835-aux.h
Note that earlier discussions on the rpi list the use of
the following existing frameworks were rejected:
* syscon - device tree should describe HW not drivers to use
('compatiblity = "brcm,bcm2835-aux-enable", "syscon";')
is not acceptable)
* regulator - the HW does not necessarily a regulator
or a power gate, so it is no valid use-case
this framework.
A new "minimal" framework was recommended instead.
Note that this is only a RFC containing everything in one patch -
documentation would get separated out to a separate patch in the
final version then containing also the spi-driver itself in the
patch-set.
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..894ff5c
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-aux.txt
@@ -0,0 +1,16 @@
+Broadcom BCM2835 auxiliar device enable register
+
+the BCM2835 contains 3 auxiliar SPI devices
+which need to get enabled via a shared register.
+
+Required properties:
+- compatible: Should be "brcm,bcm2835-aux-spi".
+- reg: Should contain register location and length for the enabl
+ register
+
+Example:
+
+aux_enable: aux_enable at 0x7e215004 {
+ compatible = "bcrm,bcm2835-aux-enable";
+ reg = <0x7e215004 0x04>;
+};
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..b26060d
--- /dev/null
+++ b/drivers/soc/bcm/Kconfig
@@ -0,0 +1,10 @@
+#
+# MediaTek SoC drivers
+#
+config SOC_BCM2835_AUX
+ tristate "Broadcom BCM2835 aux"
+ depends on OF
+ depends on ARCH_BCM2835 || COMPILE_TEST
+
+ help
+ Support for the BCM2835 auxiliar devices
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..19e50f8
--- /dev/null
+++ b/drivers/soc/bcm/bcm2835-aux.c
@@ -0,0 +1,155 @@
+/*
+ * bcm2835-aux
+ *
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * Author: Martin Sperl <kernel at 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/list.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 hw-blocks for Broadcom BCM2835 aux");
+MODULE_AUTHOR("Martin Sperl <kernel at 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..685232c
--- /dev/null
+++ b/include/linux/soc/bcm/bcm2835-aux.h
@@ -0,0 +1,24 @@
+/*
+ * 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__
+
+#include <linux/device.h>
+#include <linux/types.h>
+
+int bcm2835aux_enable(struct device *dev, const char *property);
+int bcm2835aux_disable(struct device *dev, const char *property);
+
+#endif
--
1.7.10.4
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