memory: emif: add device tree support to emif driver

Device tree support for the EMIF driver. LPDDR2 generic timings
extraction from device is managed using couple of helper
functions which can be used by other memory controller
drivers.

Reviewed-by: Benoit Cousson <b-cousson@ti.com>
Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Aneesh V <aneesh@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 153 insertions, 0 deletions

diff --git a/drivers/memory/of_memory.c b/drivers/memory/of_memory.c
new file mode 100644
index 000000000000..60074351f17e
--- /dev/null
+++ b/drivers/memory/of_memory.c
@@ -0,0 +1,153 @@
+/*
+ * OpenFirmware helpers for memory drivers
+ *
+ * Copyright (C) 2012 Texas Instruments, Inc.
+ *
+ * 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/platform_device.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/gfp.h>
+#include <memory/jedec_ddr.h>
+#include <linux/export.h>
+
+/**
+ * of_get_min_tck() - extract min timing values for ddr
+ * @np: pointer to ddr device tree node
+ * @device: device requesting for min timing values
+ *
+ * Populates the lpddr2_min_tck structure by extracting data
+ * from device tree node. Returns a pointer to the populated
+ * structure. If any error in populating the structure, returns
+ * default min timings provided by JEDEC.
+ */
+const struct lpddr2_min_tck *of_get_min_tck(struct device_node *np,
+                struct device *dev)
+{
+        int                     ret = 0;
+        struct lpddr2_min_tck   *min;
+
+        min = devm_kzalloc(dev, sizeof(*min), GFP_KERNEL);
+        if (!min)
+                goto default_min_tck;
+
+        ret |= of_property_read_u32(np, "tRPab-min-tck", &min->tRPab);
+        ret |= of_property_read_u32(np, "tRCD-min-tck", &min->tRCD);
+        ret |= of_property_read_u32(np, "tWR-min-tck", &min->tWR);
+        ret |= of_property_read_u32(np, "tRASmin-min-tck", &min->tRASmin);
+        ret |= of_property_read_u32(np, "tRRD-min-tck", &min->tRRD);
+        ret |= of_property_read_u32(np, "tWTR-min-tck", &min->tWTR);
+        ret |= of_property_read_u32(np, "tXP-min-tck", &min->tXP);
+        ret |= of_property_read_u32(np, "tRTP-min-tck", &min->tRTP);
+        ret |= of_property_read_u32(np, "tCKE-min-tck", &min->tCKE);
+        ret |= of_property_read_u32(np, "tCKESR-min-tck", &min->tCKESR);
+        ret |= of_property_read_u32(np, "tFAW-min-tck", &min->tFAW);
+
+        if (ret) {
+                devm_kfree(dev, min);
+                goto default_min_tck;
+        }
+
+        return min;
+
+default_min_tck:
+        dev_warn(dev, "%s: using default min-tck values\n", __func__);
+        return &lpddr2_jedec_min_tck;
+}
+EXPORT_SYMBOL(of_get_min_tck);
+
+static int of_do_get_timings(struct device_node *np,
+                struct lpddr2_timings *tim)
+{
+        int ret;
+
+        ret = of_property_read_u32(np, "max-freq", &tim->max_freq);
+        ret |= of_property_read_u32(np, "min-freq", &tim->min_freq);
+        ret |= of_property_read_u32(np, "tRPab", &tim->tRPab);
+        ret |= of_property_read_u32(np, "tRCD", &tim->tRCD);
+        ret |= of_property_read_u32(np, "tWR", &tim->tWR);
+        ret |= of_property_read_u32(np, "tRAS-min", &tim->tRAS_min);
+        ret |= of_property_read_u32(np, "tRRD", &tim->tRRD);
+        ret |= of_property_read_u32(np, "tWTR", &tim->tWTR);
+        ret |= of_property_read_u32(np, "tXP", &tim->tXP);
+        ret |= of_property_read_u32(np, "tRTP", &tim->tRTP);
+        ret |= of_property_read_u32(np, "tCKESR", &tim->tCKESR);
+        ret |= of_property_read_u32(np, "tDQSCK-max", &tim->tDQSCK_max);
+        ret |= of_property_read_u32(np, "tFAW", &tim->tFAW);
+        ret |= of_property_read_u32(np, "tZQCS", &tim->tZQCS);
+        ret |= of_property_read_u32(np, "tZQCL", &tim->tZQCL);
+        ret |= of_property_read_u32(np, "tZQinit", &tim->tZQinit);
+        ret |= of_property_read_u32(np, "tRAS-max-ns", &tim->tRAS_max_ns);
+        ret |= of_property_read_u32(np, "tDQSCK-max-derated",
+                &tim->tDQSCK_max_derated);
+
+        return ret;
+}
+
+/**
+ * of_get_ddr_timings() - extracts the ddr timings and updates no of
+ * frequencies available.
+ * @np_ddr: Pointer to ddr device tree node
+ * @dev: Device requesting for ddr timings
+ * @device_type: Type of ddr(LPDDR2 S2/S4)
+ * @nr_frequencies: No of frequencies available for ddr
+ * (updated by this function)
+ *
+ * Populates lpddr2_timings structure by extracting data from device
+ * tree node. Returns pointer to populated structure. If any error
+ * while populating, returns default timings provided by JEDEC.
+ */
+const struct lpddr2_timings *of_get_ddr_timings(struct device_node *np_ddr,
+                struct device *dev, u32 device_type, u32 *nr_frequencies)
+{
+        struct lpddr2_timings   *timings = NULL;
+        u32                     arr_sz = 0, i = 0;
+        struct device_node      *np_tim;
+        char                    *tim_compat;
+
+        switch (device_type) {
+        case DDR_TYPE_LPDDR2_S2:
+        case DDR_TYPE_LPDDR2_S4:
+                tim_compat = "jedec,lpddr2-timings";
+                break;
+        default:
+                dev_warn(dev, "%s: un-supported memory type\n", __func__);
+        }
+
+        for_each_child_of_node(np_ddr, np_tim)
+                if (of_device_is_compatible(np_tim, tim_compat))
+                        arr_sz++;
+
+        if (arr_sz)
+                timings = devm_kzalloc(dev, sizeof(*timings) * arr_sz,
+                        GFP_KERNEL);
+
+        if (!timings)
+                goto default_timings;
+
+        for_each_child_of_node(np_ddr, np_tim) {
+                if (of_device_is_compatible(np_tim, tim_compat)) {
+                        if (of_do_get_timings(np_tim, &timings[i])) {
+                                devm_kfree(dev, timings);
+                                goto default_timings;
+                        }
+                        i++;
+                }
+        }
+
+        *nr_frequencies = arr_sz;
+
+        return timings;
+
+default_timings:
+        dev_warn(dev, "%s: using default timings\n", __func__);
+        *nr_frequencies = ARRAY_SIZE(lpddr2_jedec_timings);
+        return lpddr2_jedec_timings;
+}
+EXPORT_SYMBOL(of_get_ddr_timings);