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Date: Thu, 12 Sep 2013 21:30:25 -0300
From: Emilio López <emilio@...pez.com.ar>
To: Mike Turquette <mturquette@...aro.org>,
Maxime Ripard <maxime.ripard@...e-electrons.com>,
grant.likely@...aro.org, rob.herring@...xeda.com,
gregkh@...uxfoundation.org
Cc: <devicetree@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, david.lanzendoerfer@....ch,
<linux-kernel@...r.kernel.org>,
Emilio López <emilio@...pez.com.ar>
Subject: [PATCH] memory: add a basic OF-based memory driver
This driver's only job is to claim and ensure the necessary clock
for memory operation on a DT-powered machine remains enabled.
Signed-off-by: Emilio López <emilio@...pez.com.ar>
---
I believe this new patch should resolve all the concerns raised; as
always, all feedback is welcome :)
Changes from RFC:
- Move from drivers/of to drivers/memory
- Make a proper driver instead of using an initcall
- Binding document for the new "simple-memory-controller"
.../simple-memory-controller.txt | 19 ++++++++
drivers/memory/Kconfig | 11 +++++
drivers/memory/Makefile | 1 +
drivers/memory/simple-mc.c | 57 ++++++++++++++++++++++
4 files changed, 88 insertions(+)
create mode 100644 Documentation/devicetree/bindings/memory-controllers/simple-memory-controller.txt
create mode 100644 drivers/memory/simple-mc.c
diff --git a/Documentation/devicetree/bindings/memory-controllers/simple-memory-controller.txt b/Documentation/devicetree/bindings/memory-controllers/simple-memory-controller.txt
new file mode 100644
index 0000000..d37683b
--- /dev/null
+++ b/Documentation/devicetree/bindings/memory-controllers/simple-memory-controller.txt
@@ -0,0 +1,19 @@
+Device Tree Clock binding for a simple memory controller.
+
+Required properties:
+- compatible : shall be "simple-memory-controller"
+
+Optional properties:
+- reg : may contain the register space for the controller. This
+ property is currently ignored by the driver
+- clocks : may contain a phandle to the clock that is currently being
+ used on the controller. This clock shall remain enabled
+ during system operation.
+
+Example:
+
+mc: mc@...3000 {
+ compatible = "simple-memory-controller";
+ reg = <0x0123000 0x400>;
+ clocks = <&pll5 1>;
+};
diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
index 29a11db..4a6df65 100644
--- a/drivers/memory/Kconfig
+++ b/drivers/memory/Kconfig
@@ -50,4 +50,15 @@ config TEGRA30_MC
analysis, especially for IOMMU/SMMU(System Memory Management
Unit) module.
+config SIMPLE_MC
+ bool "Simple memory controller"
+ default y
+ depends on OF && COMMON_CLK
+ help
+ This driver is able to manage a simple memory controller whose
+ only needs consist of keeping one clock enabled. The
+ controller must be defined on the device tree as compatible
+ with "simple-memory-controller"; see the corresponding binding
+ document for more details.
+
endif
diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
index 969d923..e0953e5 100644
--- a/drivers/memory/Makefile
+++ b/drivers/memory/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_TI_EMIF) += emif.o
obj-$(CONFIG_MVEBU_DEVBUS) += mvebu-devbus.o
obj-$(CONFIG_TEGRA20_MC) += tegra20-mc.o
obj-$(CONFIG_TEGRA30_MC) += tegra30-mc.o
+obj-$(CONFIG_SIMPLE_MC) += simple-mc.o
diff --git a/drivers/memory/simple-mc.c b/drivers/memory/simple-mc.c
new file mode 100644
index 0000000..e58371d
--- /dev/null
+++ b/drivers/memory/simple-mc.c
@@ -0,0 +1,57 @@
+/*
+ * Simple memory controller driver
+ *
+ * Copyright 2013 Emilio López <emilio@...pez.com.ar>
+ *
+ * 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/of.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+static int simple_mc_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct clk *clk;
+
+ if (!np)
+ return -ENODEV;
+
+ clk = of_clk_get(np, 0);
+ if (!IS_ERR(clk)) {
+ clk_prepare_enable(clk);
+ clk_put(clk);
+ }
+
+ return 0;
+}
+
+static const struct of_device_id simple_mc_of_match[] = {
+ { .compatible = "simple-memory-controller", },
+ { /* sentinel */ },
+};
+
+static struct platform_driver simple_mc_driver = {
+ .probe = simple_mc_probe,
+ .driver = {
+ .name = "simple-mc",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(simple_mc_of_match),
+ },
+};
+
+module_platform_driver(simple_mc_driver);
+
+MODULE_AUTHOR("Emilio López <emilio@...pez.com.ar>");
+MODULE_DESCRIPTION("Simple memory controller driver");
+MODULE_LICENSE("GPL");
--
1.8.4
--
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