soc: ti: pruss: Add support for PRU-ICSSs on AM437x SoCs

The AM437x SoCs have two different PRU-ICSS subsystems: PRU-ICSS1
and a smaller PRU-ICSS0. Enhance the PRUSS platform driver to support
both the PRU-ICSS sub-systems on these SoCs.

The PRU-ICSS1 on AM437x is very similar to the PRU-ICSS on AM33xx
except for few minor differences - increased Instruction RAM, increased
Shared Data RAM2, and 1 less interrupt (PRUSS host interrupt 7 which is
redirected to the other PRUSS) towards the MPU INTC. The PRU-ICSS0 is
a cut-down version of the IP, with less DRAM per PRU, no Shared DRAM etc.
It also does not have direct access to L3 bus regions, there is a single
interface to L3 for both PRUSS0 and PRUSS1, and it would have to go
through the PRUSS1's interface. The PRUSS_SYSCFG register is reserved on
PRUSS0, so any external access requires the programming the corresponding
PRUSS_SYSCFG register in PRUSS1. It does have its own dedicated I/O lines
though. Note that this instance does not support any PRU Ethernet related
use cases.

The adaptation uses SoC-specific compatibles in the driver and uses
a newly introduced pruss_match_private_data structure and the
pruss_get_private_data() function to retrieve a PRUSS instance specific
data using a device-name based lookup logic. The reset and the L3 external
access are managed by the parent interconnect ti-sysc bus driver so that
PRUSS1 and PRUSS0 can be independently supported.
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

drivers/soc/ti/Kconfig

@@ -103,7 +103,7 @@ config TI_K3_SOCINFO
 
 config TI_PRUSS
 	tristate "TI PRU-ICSS Subsystem Platform drivers"
-	depends on SOC_AM33XX
+	depends on SOC_AM33XX || SOC_AM43XX
 	select MFD_SYSCON
 	help
 	  TI PRU-ICSS Subsystem platform specific support.

drivers/soc/ti/pruss.c

@@ -17,6 +17,14 @@
 #include <linux/pm_runtime.h>
 #include <linux/pruss_driver.h>
 
+/**
+ * struct pruss_private_data - PRUSS driver private data
+ * @has_no_sharedram: flag to indicate the absence of PRUSS Shared Data RAM
+ */
+struct pruss_private_data {
+	bool has_no_sharedram;
+};
+
 static int pruss_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -25,8 +33,15 @@ static int pruss_probe(struct platform_device *pdev)
 	struct pruss *pruss;
 	struct resource res;
 	int ret, i, index;
+	const struct pruss_private_data *data;
 	const char *mem_names[PRUSS_MEM_MAX] = { "dram0", "dram1", "shrdram2" };
 
+	data = of_device_get_match_data(&pdev->dev);
+	if (IS_ERR(data)) {
+		dev_err(dev, "missing private data\n");
+		return -ENODEV;
+	}
+
 	ret = dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
 	if (ret) {
 		dev_err(dev, "failed to set the DMA coherent mask");
@@ -45,7 +60,14 @@ static int pruss_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	for (i = 0; i < ARRAY_SIZE(mem_names); i++) {
+	for (i = 0; i < PRUSS_MEM_MAX; i++) {
+		/*
+		 * On AM437x one of two PRUSS units don't contain Shared RAM,
+		 * skip it
+		 */
+		if (data && data->has_no_sharedram && i == PRUSS_MEM_SHRD_RAM2)
+			continue;
+
 		index = of_property_match_string(child, "reg-names",
 						 mem_names[i]);
 		if (index < 0) {
@@ -126,8 +148,19 @@ static int pruss_remove(struct platform_device *pdev)
 	return 0;
 }
 
+/* instance-specific driver private data */
+static const struct pruss_private_data am437x_pruss1_data = {
+	.has_no_sharedram = false,
+};
+
+static const struct pruss_private_data am437x_pruss0_data = {
+	.has_no_sharedram = true,
+};
+
 static const struct of_device_id pruss_of_match[] = {
 	{ .compatible = "ti,am3356-pruss" },
+	{ .compatible = "ti,am4376-pruss0", .data = &am437x_pruss0_data, },
+	{ .compatible = "ti,am4376-pruss1", .data = &am437x_pruss1_data, },
 	{},
 };
 MODULE_DEVICE_TABLE(of, pruss_of_match);