drivers: bus: add a new driver for WEIM

The WEIM(Wireless External Interface Module) works like a bus.
You can attach many different devices on it, such as NOR, onenand.

In the case of i.MX6q-sabreauto, the NOR is connected to WEIM.

This patch also adds the devicetree binding document.
The driver only works when the devicetree is enabled.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

4 files changed, 197 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/bus/imx-weim.txt b/Documentation/devicetree/bindings/bus/imx-weim.txt
new file mode 100644
index 000000000000..cedc2a9c4785
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/imx-weim.txt
@@ -0,0 +1,49 @@
+Device tree bindings for i.MX Wireless External Interface Module (WEIM)
+
+The term "wireless" does not imply that the WEIM is literally an interface
+without wires. It simply means that this module was originally designed for
+wireless and mobile applications that use low-power technology.
+
+The actual devices are instantiated from the child nodes of a WEIM node.
+
+Required properties:
+
+ - compatible:          Should be set to "fsl,imx6q-weim"
+ - reg:                 A resource specifier for the register space
+                        (see the example below)
+ - clocks:              the clock, see the example below.
+ - #address-cells:      Must be set to 2 to allow memory address translation
+ - #size-cells:         Must be set to 1 to allow CS address passing
+ - ranges:              Must be set up to reflect the memory layout with four
+                        integer values for each chip-select line in use:
+
+                           <cs-number> 0 <physical address of mapping> <size>
+
+Timing property for child nodes. It is mandatory, not optional.
+
+ - fsl,weim-cs-timing:  The timing array, contains 6 timing values for the
+                        child node. We can get the CS index from the child
+                        node's "reg" property. This property contains the values
+                        for the registers EIM_CSnGCR1, EIM_CSnGCR2, EIM_CSnRCR1,
+                        EIM_CSnRCR2, EIM_CSnWCR1, EIM_CSnWCR2 in this order.
+
+Example for an imx6q-sabreauto board, the NOR flash connected to the WEIM:
+
+        weim: weim@021b8000 {
+                compatible = "fsl,imx6q-weim";
+                reg = <0x021b8000 0x4000>;
+                clocks = <&clks 196>;
+                #address-cells = <2>;
+                #size-cells = <1>;
+                ranges = <0 0 0x08000000 0x08000000>;
+
+                nor@0,0 {
+                        compatible = "cfi-flash";
+                        reg = <0 0 0x02000000>;
+                        #address-cells = <1>;
+                        #size-cells = <1>;
+                        bank-width = <2>;
+                        fsl,weim-cs-timing = <0x00620081 0x00000001 0x1c022000
+                                        0x0000c000 0x1404a38e 0x00000000>;
+                };
+        };
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index b05ecab915c4..46cd5bb098a9 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -4,6 +4,15 @@
 
 menu "Bus devices"
 
+config IMX_WEIM
+        bool "Freescale EIM DRIVER"
+        depends on ARCH_MXC
+        help
+          Driver for i.MX6 WEIM controller.
+          The WEIM(Wireless External Interface Module) works like a bus.
+          You can attach many different devices on it, such as NOR, onenand.
+          But now, we only support the Parallel NOR.
+
 config MVEBU_MBUS
         bool
         depends on PLAT_ORION
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 3c7b53c12091..436bbccf4894 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -2,6 +2,7 @@
 # Makefile for the bus drivers.
 #
 
+obj-$(CONFIG_IMX_WEIM)  += imx-weim.o
 obj-$(CONFIG_MVEBU_MBUS) += mvebu-mbus.o
 obj-$(CONFIG_OMAP_OCP2SCP)      += omap-ocp2scp.o
 
diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
new file mode 100644
index 000000000000..349f14e886b7
--- /dev/null
+++ b/drivers/bus/imx-weim.c
@@ -0,0 +1,138 @@
+/*
+ * EIM driver for Freescale's i.MX chips
+ *
+ * Copyright (C) 2013 Freescale Semiconductor, Inc.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/of_device.h>
+
+struct imx_weim {
+        void __iomem *base;
+        struct clk *clk;
+};
+
+static const struct of_device_id weim_id_table[] = {
+        { .compatible = "fsl,imx6q-weim", },
+        {}
+};
+MODULE_DEVICE_TABLE(of, weim_id_table);
+
+#define CS_TIMING_LEN 6
+#define CS_REG_RANGE  0x18
+
+/* Parse and set the timing for this device. */
+static int
+weim_timing_setup(struct platform_device *pdev, struct device_node *np)
+{
+        struct imx_weim *weim = platform_get_drvdata(pdev);
+        u32 value[CS_TIMING_LEN];
+        u32 cs_idx;
+        int ret;
+        int i;
+
+        /* get the CS index from this child node's "reg" property. */
+        ret = of_property_read_u32(np, "reg", &cs_idx);
+        if (ret)
+                return ret;
+
+        /* The weim has four chip selects. */
+        if (cs_idx > 3)
+                return -EINVAL;
+
+        ret = of_property_read_u32_array(np, "fsl,weim-cs-timing",
+                                        value, CS_TIMING_LEN);
+        if (ret)
+                return ret;
+
+        /* set the timing for WEIM */
+        for (i = 0; i < CS_TIMING_LEN; i++)
+                writel(value[i], weim->base + cs_idx * CS_REG_RANGE + i * 4);
+        return 0;
+}
+
+static int weim_parse_dt(struct platform_device *pdev)
+{
+        struct device_node *child;
+        int ret;
+
+        for_each_child_of_node(pdev->dev.of_node, child) {
+                if (!child->name)
+                        continue;
+
+                ret = weim_timing_setup(pdev, child);
+                if (ret) {
+                        dev_err(&pdev->dev, "%s set timing failed.\n",
+                                child->full_name);
+                        return ret;
+                }
+        }
+
+        ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+        if (ret)
+                dev_err(&pdev->dev, "%s fail to create devices.\n",
+                        pdev->dev.of_node->full_name);
+        return ret;
+}
+
+static int weim_probe(struct platform_device *pdev)
+{
+        struct imx_weim *weim;
+        struct resource *res;
+        int ret = -EINVAL;
+
+        weim = devm_kzalloc(&pdev->dev, sizeof(*weim), GFP_KERNEL);
+        if (!weim) {
+                ret = -ENOMEM;
+                goto weim_err;
+        }
+        platform_set_drvdata(pdev, weim);
+
+        /* get the resource */
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        weim->base = devm_ioremap_resource(&pdev->dev, res);
+        if (IS_ERR(weim->base)) {
+                ret = PTR_ERR(weim->base);
+                goto weim_err;
+        }
+
+        /* get the clock */
+        weim->clk = devm_clk_get(&pdev->dev, NULL);
+        if (IS_ERR(weim->clk))
+                goto weim_err;
+
+        ret = clk_prepare_enable(weim->clk);
+        if (ret)
+                goto weim_err;
+
+        /* parse the device node */
+        ret = weim_parse_dt(pdev);
+        if (ret) {
+                clk_disable_unprepare(weim->clk);
+                goto weim_err;
+        }
+
+        dev_info(&pdev->dev, "WEIM driver registered.\n");
+        return 0;
+
+weim_err:
+        return ret;
+}
+
+static struct platform_driver weim_driver = {
+        .driver = {
+                .name = "imx-weim",
+                .of_match_table = weim_id_table,
+        },
+        .probe   = weim_probe,
+};
+
+module_platform_driver(weim_driver);
+MODULE_AUTHOR("Freescale Semiconductor Inc.");
+MODULE_DESCRIPTION("i.MX EIM Controller Driver");
+MODULE_LICENSE("GPL");