bus: imx-weim: support CS GPR configuration

For imx50-weim and imx6q-weim type of devices, there might a WEIM CS
space configuration register in General Purpose Register controller,
e.g. IOMUXC_GPR1 on i.MX6Q.

Depending on which configuration of the following 4 is chosen for given
system, IOMUXC_GPR1[11:0] should be set up as 05, 033, 0113 or 01111
correspondingly.

	CS0(128M) CS1(0M)  CS2(0M)  CS3(0M)
	CS0(64M)  CS1(64M) CS2(0M)  CS3(0M)
	CS0(64M)  CS1(32M) CS2(32M) CS3(0M)
	CS0(32M)  CS1(32M) CS2(32M) CS3(32M)

The patch creates a function for such type of devices, which scans
'ranges' property of WEIM node and build the GPR value incrementally.
Thus the WEIM CS GPR can be set up automatically at boot time.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Philippe De Muyter <phdm@macqel.be>
Tested-by: Philippe De Muyter <phdm@macqel.be>

1 files changed, 58 insertions, 0 deletions

diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
index 3ef58c8dbf11..f8ee13c7bf7b 100644
--- a/drivers/bus/imx-weim.c
+++ b/drivers/bus/imx-weim.c
@@ -11,6 +11,9 @@
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/of_device.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
+#include <linux/regmap.h>
 
 struct imx_weim_devtype {
         unsigned int    cs_count;
@@ -56,6 +59,55 @@ static const struct of_device_id weim_id_table[] = {
 };
 MODULE_DEVICE_TABLE(of, weim_id_table);
 
+static int __init imx_weim_gpr_setup(struct platform_device *pdev)
+{
+        struct device_node *np = pdev->dev.of_node;
+        struct property *prop;
+        const __be32 *p;
+        struct regmap *gpr;
+        u32 gprvals[4] = {
+                05,     /* CS0(128M) CS1(0M)  CS2(0M)  CS3(0M)  */
+                033,    /* CS0(64M)  CS1(64M) CS2(0M)  CS3(0M)  */
+                0113,   /* CS0(64M)  CS1(32M) CS2(32M) CS3(0M)  */
+                01111,  /* CS0(32M)  CS1(32M) CS2(32M) CS3(32M) */
+        };
+        u32 gprval = 0;
+        u32 val;
+        int cs = 0;
+        int i = 0;
+
+        gpr = syscon_regmap_lookup_by_phandle(np, "fsl,weim-cs-gpr");
+        if (IS_ERR(gpr)) {
+                dev_dbg(&pdev->dev, "failed to find weim-cs-gpr\n");
+                return 0;
+        }
+
+        of_property_for_each_u32(np, "ranges", prop, p, val) {
+                if (i % 4 == 0) {
+                        cs = val;
+                } else if (i % 4 == 3 && val) {
+                        val = (val / SZ_32M) | 1;
+                        gprval |= val << cs * 3;
+                }
+                i++;
+        }
+
+        if (i == 0 || i % 4)
+                goto err;
+
+        for (i = 0; i < ARRAY_SIZE(gprvals); i++) {
+                if (gprval == gprvals[i]) {
+                        /* Found it. Set up IOMUXC_GPR1[11:0] with it. */
+                        regmap_update_bits(gpr, IOMUXC_GPR1, 0xfff, gprval);
+                        return 0;
+                }
+        }
+
+err:
+        dev_err(&pdev->dev, "Invalid 'ranges' configuration\n");
+        return -EINVAL;
+}
+
 /* Parse and set the timing for this device. */
 static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
                                     const struct imx_weim_devtype *devtype)
@@ -92,6 +144,12 @@ static int __init weim_parse_dt(struct platform_device *pdev,
         struct device_node *child;
         int ret;
 
+        if (devtype == &imx50_weim_devtype) {
+                ret = imx_weim_gpr_setup(pdev);
+                if (ret)
+                        return ret;
+        }
+
         for_each_child_of_node(pdev->dev.of_node, child) {
                 if (!child->name)
                         continue;