[PATCH v2] lib: utils/irqchip: Automatically delegate T-HEAD PLIC access

[Samuel Holland]

The T-HEAD PLIC implementation requires setting a delegation bit
to allow access from S-mode. Now that the T-HEAD PLIC has its own
compatible string, set this bit automatically from the PLIC driver,
instead of reaching into the PLIC's MMIO space from another driver.

Signed-off-by: Samuel Holland <samuel at sholland.org>

---

Changes in v2:
 - Use the thead,c900-plic compatible instead of the D1 compatible.
 - Also apply this change to other T-HEAD device tree examples.
 - Remove the plic-delegate code from the thead,reset-sample driver.
 - Drop the return value from thead_plic_plat_init().

The compatible string is added in the patch series here:
https://lore.kernel.org/linux-riscv/20211016032200.2869998-1-guoren@kernel.org/T/
---
 docs/platform/thead-c9xx.md          | 12 +++---------
 lib/utils/irqchip/fdt_irqchip_plic.c | 15 +++++++++++++++
 lib/utils/reset/fdt_reset_thead.c    |  8 --------
 3 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/docs/platform/thead-c9xx.md b/docs/platform/thead-c9xx.md
index c0daeb7..3490ed5 100644
--- a/docs/platform/thead-c9xx.md
+++ b/docs/platform/thead-c9xx.md
@@ -51,11 +51,6 @@ DTS Example1: (Single core, eg: Allwinner D1 - c906)
 		compatible = "simple-bus";
 		ranges;
 
-		reset: reset-sample {
-			compatible = "thead,reset-sample";
-			plic-delegate = <0x0 0x101ffffc>;
-		};
-
 		clint0: clint at 14000000 {
 			compatible = "riscv,clint0";
 			interrupts-extended = <
@@ -67,7 +62,8 @@ DTS Example1: (Single core, eg: Allwinner D1 - c906)
 
 		intc: interrupt-controller at 10000000 {
 			#interrupt-cells = <1>;
-			compatible = "riscv,plic0";
+			compatible = "allwinner,sun20i-d1-plic",
+				     "thead,c900-plic";
 			interrupt-controller;
 			interrupts-extended = <
 				&cpu0_intc  0xffffffff &cpu0_intc  9
@@ -150,7 +146,6 @@ DTS Example2: (Multi cores with soc reset-regs)
 
 		reset: reset-sample {
 			compatible = "thead,reset-sample";
-			plic-delegate = <0xff 0xd81ffffc>;
 			entry-reg = <0xff 0xff019050>;
 			entry-cnt = <4>;
 			control-reg = <0xff 0xff015004>;
@@ -173,7 +168,7 @@ DTS Example2: (Multi cores with soc reset-regs)
 
 		intc: interrupt-controller at ffd8000000 {
 			#interrupt-cells = <1>;
-			compatible = "riscv,plic0";
+			compatible = "thead,c900-plic";
 			interrupt-controller;
 			interrupts-extended = <
 				&cpu0_intc  0xffffffff &cpu0_intc  9
@@ -194,7 +189,6 @@ DTS Example2: (Multi cores with old reset csrs)
 ```
 	reset: reset-sample {
 		compatible = "thead,reset-sample";
-		plic-delegate = <0xff 0xd81ffffc>;
 		using-csr-reset;
 		csr-copy = <0x7c0 0x7c1 0x7c2 0x7c3 0x7c5 0x7cc
 			    0x3b0 0x3b1 0x3b2 0x3b3
diff --git a/lib/utils/irqchip/fdt_irqchip_plic.c b/lib/utils/irqchip/fdt_irqchip_plic.c
index 18d2797..8d375be 100644
--- a/lib/utils/irqchip/fdt_irqchip_plic.c
+++ b/lib/utils/irqchip/fdt_irqchip_plic.c
@@ -9,6 +9,7 @@
 
 #include <libfdt.h>
 #include <sbi/riscv_asm.h>
+#include <sbi/riscv_io.h>
 #include <sbi/sbi_error.h>
 #include <sbi/sbi_hartmask.h>
 #include <sbi_utils/fdt/fdt_helper.h>
@@ -91,6 +92,11 @@ static int irqchip_plic_cold_init(void *fdt, int nodeoff,
 	if (rc)
 		return rc;
 
+	if (match->data) {
+		void (*plic_plat_init)(struct plic_data *) = match->data;
+		plic_plat_init(pd);
+	}
+
 	rc = plic_cold_irqchip_init(pd);
 	if (rc)
 		return rc;
@@ -106,9 +112,18 @@ static int irqchip_plic_cold_init(void *fdt, int nodeoff,
 	return irqchip_plic_update_hartid_table(fdt, nodeoff, pd);
 }
 
+#define THEAD_PLIC_CTRL_REG 0x1ffffc
+
+static void thead_plic_plat_init(struct plic_data *pd)
+{
+	writel_relaxed(BIT(0), (void *)pd->addr + THEAD_PLIC_CTRL_REG);
+}
+
 static const struct fdt_match irqchip_plic_match[] = {
 	{ .compatible = "riscv,plic0" },
 	{ .compatible = "sifive,plic-1.0.0" },
+	{ .compatible = "thead,c900-plic",
+	  .data = thead_plic_plat_init },
 	{ },
 };
 
diff --git a/lib/utils/reset/fdt_reset_thead.c b/lib/utils/reset/fdt_reset_thead.c
index 750b7aa..d491687 100644
--- a/lib/utils/reset/fdt_reset_thead.c
+++ b/lib/utils/reset/fdt_reset_thead.c
@@ -82,14 +82,6 @@ static int thead_reset_init(void *fdt, int nodeoff,
 			clone_csrs(cnt);
 	}
 
-
-	/* Delegate plic enable regs for S-mode */
-	val = fdt_getprop(fdt, nodeoff, "plic-delegate", &len);
-	if (len > 0 && val) {
-		p = (void *)(ulong)fdt64_to_cpu(*val);
-		writel(BIT(0), p);
-	}
-
 	/* Old reset method for secondary harts */
 	if (fdt_getprop(fdt, nodeoff, "using-csr-reset", &len)) {
 		csr_write(0x7c7, (ulong)&__thead_pre_start_warm);
-- 
2.32.0