ARM: OMAP2+: Add function to read GPMC settings from device-tree

Adds a function to read the various GPMC chip-select settings from
device-tree and store them in the gpmc_settings structure.

Update the GPMC device-tree binding documentation to describe these
options.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>

3 files changed, 65 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/bus/ti-gpmc.txt b/Documentation/devicetree/bindings/bus/ti-gpmc.txt
index 5ddb2e9efaaa..6fde1cfe51f8 100644
--- a/Documentation/devicetree/bindings/bus/ti-gpmc.txt
+++ b/Documentation/devicetree/bindings/bus/ti-gpmc.txt
@@ -65,6 +65,29 @@ The following are only applicable to OMAP3+ and AM335x:
  - gpmc,wr-access
  - gpmc,wr-data-mux-bus
 
+GPMC chip-select settings properties for child nodes. All are optional.
+
+- gpmc,burst-length     Page/burst length. Must be 4, 8 or 16.
+- gpmc,burst-wrap       Enables wrap bursting
+- gpmc,burst-read       Enables read page/burst mode
+- gpmc,burst-write      Enables write page/burst mode
+- gpmc,device-nand      Device is NAND
+- gpmc,device-width     Total width of device(s) connected to a GPMC
+                        chip-select in bytes. The GPMC supports 8-bit
+                        and 16-bit devices and so this property must be
+                        1 or 2.
+- gpmc,mux-add-data     Address and data multiplexing configuration.
+                        Valid values are 1 for address-address-data
+                        multiplexing mode and 2 for address-data
+                        multiplexing mode.
+- gpmc,sync-read        Enables synchronous read. Defaults to asynchronous
+                        is this is not set.
+- gpmc,sync-write       Enables synchronous writes. Defaults to asynchronous
+                        is this is not set.
+- gpmc,wait-pin         Wait-pin used by client. Must be less than
+                        "gpmc,num-waitpins".
+- gpmc,wait-on-read     Enables wait monitoring on reads.
+- gpmc,wait-on-write    Enables wait monitoring on writes.
 
 Example for an AM33xx board:
 
diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index b22771b4d9f2..85231b3a217e 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -1187,6 +1187,46 @@ static struct of_device_id gpmc_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, gpmc_dt_ids);
 
+/**
+ * gpmc_read_settings_dt - read gpmc settings from device-tree
+ * @np:         pointer to device-tree node for a gpmc child device
+ * @p:          pointer to gpmc settings structure
+ *
+ * Reads the GPMC settings for a GPMC child device from device-tree and
+ * stores them in the GPMC settings structure passed. The GPMC settings
+ * structure is initialised to zero by this function and so any
+ * previously stored settings will be cleared.
+ */
+void gpmc_read_settings_dt(struct device_node *np, struct gpmc_settings *p)
+{
+        memset(p, 0, sizeof(struct gpmc_settings));
+
+        p->sync_read = of_property_read_bool(np, "gpmc,sync-read");
+        p->sync_write = of_property_read_bool(np, "gpmc,sync-write");
+        p->device_nand = of_property_read_bool(np, "gpmc,device-nand");
+        of_property_read_u32(np, "gpmc,device-width", &p->device_width);
+        of_property_read_u32(np, "gpmc,mux-add-data", &p->mux_add_data);
+
+        if (!of_property_read_u32(np, "gpmc,burst-length", &p->burst_len)) {
+                p->burst_wrap = of_property_read_bool(np, "gpmc,burst-wrap");
+                p->burst_read = of_property_read_bool(np, "gpmc,burst-read");
+                p->burst_write = of_property_read_bool(np, "gpmc,burst-write");
+                if (!p->burst_read && !p->burst_write)
+                        pr_warn("%s: page/burst-length set but not used!\n",
+                                __func__);
+        }
+
+        if (!of_property_read_u32(np, "gpmc,wait-pin", &p->wait_pin)) {
+                p->wait_on_read = of_property_read_bool(np,
+                                                        "gpmc,wait-on-read");
+                p->wait_on_write = of_property_read_bool(np,
+                                                         "gpmc,wait-on-write");
+                if (!p->wait_on_read && !p->wait_on_write)
+                        pr_warn("%s: read/write wait monitoring not enabled!\n",
+                                __func__);
+        }
+}
+
 static void __maybe_unused gpmc_read_timings_dt(struct device_node *np,
                                                 struct gpmc_timings *gpmc_t)
 {
diff --git a/arch/arm/mach-omap2/gpmc.h b/arch/arm/mach-omap2/gpmc.h
index 87d2a226a3ba..707f6d58edd5 100644
--- a/arch/arm/mach-omap2/gpmc.h
+++ b/arch/arm/mach-omap2/gpmc.h
@@ -225,5 +225,7 @@ extern void gpmc_cs_free(int cs);
 extern void omap3_gpmc_save_context(void);
 extern void omap3_gpmc_restore_context(void);
 extern int gpmc_configure(int cmd, int wval);
+extern void gpmc_read_settings_dt(struct device_node *np,
+                                  struct gpmc_settings *p);
 
 #endif