remoteproc: k3-r5: Add loading support for on-chip SRAM regions

The K3 SoCs has various internal on-chip SRAM memories like the SRAM
within the MCU domain or the shared MSMC RAM within NavSS that can be
used for multiple purposes. One such purpose is to have the R5F cores
use a portion of such on-chip SRAM for fast-access data or to directly
execute code.

Add support to the K3 R5 remoteproc driver to parse and support
loading into such memories. The SRAM regions need to be mapped as
normal non-cacheable memory to avoid kernel crashes when the remoteproc
loader code uses the Arm64 memset library function (the "DC ZVA"
instruction throws a alignment fault on device type memory).

These SRAM regions are completely optional as not all firmware images
require these memories, and any such memory has to be reserved as such
in the DTS files.

Signed-off-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20201002234234.20704-5-s-anna@ti.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/ti_k3_r5_remoteproc.c

@@ -85,7 +85,9 @@ struct k3_r5_cluster {
  * @dev: cached device pointer
  * @rproc: rproc handle representing this core
  * @mem: internal memory regions data
+ * @sram: on-chip SRAM memory regions data
  * @num_mems: number of internal memory regions
+ * @num_sram: number of on-chip SRAM memory regions
  * @reset: reset control handle
  * @tsp: TI-SCI processor control handle
  * @ti_sci: TI-SCI handle
@@ -99,7 +101,9 @@ struct k3_r5_core {
 	struct device *dev;
 	struct rproc *rproc;
 	struct k3_r5_mem *mem;
+	struct k3_r5_mem *sram;
 	int num_mems;
+	int num_sram;
 	struct reset_control *reset;
 	struct ti_sci_proc *tsp;
 	const struct ti_sci_handle *ti_sci;
@@ -587,6 +591,18 @@ static void *k3_r5_rproc_da_to_va(struct rproc *rproc, u64 da, size_t len)
 		}
 	}
 
+	/* handle any SRAM regions using SoC-view addresses */
+	for (i = 0; i < core->num_sram; i++) {
+		dev_addr = core->sram[i].dev_addr;
+		size = core->sram[i].size;
+
+		if (da >= dev_addr && ((da + len) <= (dev_addr + size))) {
+			offset = da - dev_addr;
+			va = core->sram[i].cpu_addr + offset;
+			return (__force void *)va;
+		}
+	}
+
 	/* handle static DDR reserved memory regions */
 	for (i = 0; i < kproc->num_rmems; i++) {
 		dev_addr = kproc->rmem[i].dev_addr;
@@ -1027,6 +1043,63 @@ static int k3_r5_core_of_get_internal_memories(struct platform_device *pdev,
 	return 0;
 }
 
+static int k3_r5_core_of_get_sram_memories(struct platform_device *pdev,
+					   struct k3_r5_core *core)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct device_node *sram_np;
+	struct resource res;
+	int num_sram;
+	int i, ret;
+
+	num_sram = of_property_count_elems_of_size(np, "sram", sizeof(phandle));
+	if (num_sram <= 0) {
+		dev_dbg(dev, "device does not use reserved on-chip memories, num_sram = %d\n",
+			num_sram);
+		return 0;
+	}
+
+	core->sram = devm_kcalloc(dev, num_sram, sizeof(*core->sram), GFP_KERNEL);
+	if (!core->sram)
+		return -ENOMEM;
+
+	for (i = 0; i < num_sram; i++) {
+		sram_np = of_parse_phandle(np, "sram", i);
+		if (!sram_np)
+			return -EINVAL;
+
+		if (!of_device_is_available(sram_np)) {
+			of_node_put(sram_np);
+			return -EINVAL;
+		}
+
+		ret = of_address_to_resource(sram_np, 0, &res);
+		of_node_put(sram_np);
+		if (ret)
+			return -EINVAL;
+
+		core->sram[i].bus_addr = res.start;
+		core->sram[i].dev_addr = res.start;
+		core->sram[i].size = resource_size(&res);
+		core->sram[i].cpu_addr = devm_ioremap_wc(dev, res.start,
+							 resource_size(&res));
+		if (!core->sram[i].cpu_addr) {
+			dev_err(dev, "failed to parse and map sram%d memory at %pad\n",
+				i, &res.start);
+			return -ENOMEM;
+		}
+
+		dev_dbg(dev, "memory sram%d: bus addr %pa size 0x%zx va %pK da 0x%x\n",
+			i, &core->sram[i].bus_addr,
+			core->sram[i].size, core->sram[i].cpu_addr,
+			core->sram[i].dev_addr);
+	}
+	core->num_sram = num_sram;
+
+	return 0;
+}
+
 static
 struct ti_sci_proc *k3_r5_core_of_get_tsp(struct device *dev,
 					  const struct ti_sci_handle *sci)
@@ -1142,6 +1215,12 @@ static int k3_r5_core_of_init(struct platform_device *pdev)
 		goto err;
 	}
 
+	ret = k3_r5_core_of_get_sram_memories(pdev, core);
+	if (ret) {
+		dev_err(dev, "failed to get sram memories, ret = %d\n", ret);
+		goto err;
+	}
+
 	ret = ti_sci_proc_request(core->tsp);
 	if (ret < 0) {
 		dev_err(dev, "ti_sci_proc_request failed, ret = %d\n", ret);