[PATCH 2/2] lib: utils/sys: Extend HTIF library to allow custom base address

[Anup Patel]

Some of RISC-V emulators provide HTIF at fixed base address so for
such emulators users have to hard-code HTIF base address in the
linker script.

To address this problem, we let users optionally provide fixed HTIF
base address via platform support (or device tree).

Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
 include/sbi_utils/sys/htif.h       |  4 +-
 lib/utils/reset/fdt_reset_htif.c   |  8 +++-
 lib/utils/serial/fdt_serial_htif.c |  8 +++-
 lib/utils/sys/htif.c               | 74 ++++++++++++++++++++++++++----
 4 files changed, 80 insertions(+), 14 deletions(-)

diff --git a/include/sbi_utils/sys/htif.h b/include/sbi_utils/sys/htif.h
index 9cc9634..106a096 100644
--- a/include/sbi_utils/sys/htif.h
+++ b/include/sbi_utils/sys/htif.h
@@ -10,8 +10,8 @@
 
 #include <sbi/sbi_types.h>
 
-int htif_serial_init(void);
+int htif_serial_init(bool custom_base, unsigned long custom_base_addr);
 
-int htif_system_reset_init(void);
+int htif_system_reset_init(bool custom_base, unsigned long custom_base_addr);
 
 #endif
diff --git a/lib/utils/reset/fdt_reset_htif.c b/lib/utils/reset/fdt_reset_htif.c
index dd08660..ab55198 100644
--- a/lib/utils/reset/fdt_reset_htif.c
+++ b/lib/utils/reset/fdt_reset_htif.c
@@ -14,7 +14,13 @@
 static int htif_reset_init(void *fdt, int nodeoff,
 			   const struct fdt_match *match)
 {
-	return htif_system_reset_init();
+	bool custom;
+	uint64_t addr = 0;
+
+	custom = fdt_get_node_addr_size(fdt, nodeoff, 0, &addr, NULL) ?
+		 false : true;
+
+	return htif_system_reset_init(custom, addr);
 }
 
 static const struct fdt_match htif_reset_match[] = {
diff --git a/lib/utils/serial/fdt_serial_htif.c b/lib/utils/serial/fdt_serial_htif.c
index fae55b8..e8bdbb4 100644
--- a/lib/utils/serial/fdt_serial_htif.c
+++ b/lib/utils/serial/fdt_serial_htif.c
@@ -19,7 +19,13 @@ static const struct fdt_match serial_htif_match[] = {
 static int serial_htif_init(void *fdt, int nodeoff,
 			    const struct fdt_match *match)
 {
-	return htif_serial_init();
+	bool custom;
+	uint64_t addr = 0;
+
+	custom = fdt_get_node_addr_size(fdt, nodeoff, 0, &addr, NULL) ?
+		 false : true;
+
+	return htif_serial_init(custom, addr);
 }
 
 struct fdt_serial fdt_serial_htif = {
diff --git a/lib/utils/sys/htif.c b/lib/utils/sys/htif.c
index 7c69c7f..fbee4c7 100644
--- a/lib/utils/sys/htif.c
+++ b/lib/utils/sys/htif.c
@@ -7,6 +7,7 @@
 
 #include <sbi/riscv_locks.h>
 #include <sbi/sbi_console.h>
+#include <sbi/sbi_error.h>
 #include <sbi/sbi_system.h>
 #include <sbi_utils/sys/htif.h>
 
@@ -47,15 +48,45 @@
 
 volatile uint64_t tohost __attribute__((section(".htif")));
 volatile uint64_t fromhost __attribute__((section(".htif")));
+
+static uint64_t *htif_base = NULL;
+static bool htif_have_base = false;
+
 static int htif_console_buf;
 static spinlock_t htif_lock = SPIN_LOCK_INITIALIZER;
 
+static inline uint64_t __read_tohost(void)
+{
+	return (htif_have_base) ? htif_base[1] : tohost;
+}
+
+static inline void __write_tohost(uint64_t val)
+{
+	if (htif_have_base)
+		htif_base[1] = val;
+	else
+		tohost = val;
+}
+
+static inline uint64_t __read_fromhost(void)
+{
+	return (htif_have_base) ? htif_base[0] : fromhost;
+}
+
+static inline void __write_fromhost(uint64_t val)
+{
+	if (htif_have_base)
+		htif_base[0] = val;
+	else
+		fromhost = val;
+}
+
 static void __check_fromhost()
 {
-	uint64_t fh = fromhost;
+	uint64_t fh = __read_fromhost();
 	if (!fh)
 		return;
-	fromhost = 0;
+	__write_fromhost(0);
 
 	/* this should be from the console */
 	if (FROMHOST_DEV(fh) != HTIF_DEV_CONSOLE)
@@ -73,9 +104,22 @@ static void __check_fromhost()
 
 static void __set_tohost(uint64_t dev, uint64_t cmd, uint64_t data)
 {
-	while (tohost)
+	while (__read_tohost())
 		__check_fromhost();
-	tohost = TOHOST_CMD(dev, cmd, data);
+	__write_tohost(TOHOST_CMD(dev, cmd, data));
+}
+
+static int set_custom_base(bool custom_base, unsigned long custom_base_addr)
+{
+	if (custom_base) {
+		if (htif_have_base &&
+		    custom_base_addr != (unsigned long)htif_base)
+			return SBI_EINVAL;
+		htif_have_base = true;
+		htif_base = (uint64_t *)custom_base_addr;
+	}
+
+	return 0;
 }
 
 #if __riscv_xlen == 32
@@ -148,10 +192,15 @@ static struct sbi_console_device htif_console = {
 	.console_getc = htif_getc
 };
 
-int htif_serial_init(void)
+int htif_serial_init(bool custom_base, unsigned long custom_base_addr)
 {
-	sbi_console_set_device(&htif_console);
+	int rc;
+
+	rc = set_custom_base(custom_base, custom_base_addr);
+	if (rc)
+		return rc;
 
+	sbi_console_set_device(&htif_console);
 	return 0;
 }
 
@@ -163,8 +212,8 @@ static int htif_system_reset_check(u32 type, u32 reason)
 static void htif_system_reset(u32 type, u32 reason)
 {
 	while (1) {
-		fromhost = 0;
-		tohost = 1;
+		__write_fromhost(0);
+		__write_tohost(1);
 	}
 }
 
@@ -174,9 +223,14 @@ static struct sbi_system_reset_device htif_reset = {
 	.system_reset = htif_system_reset
 };
 
-int htif_system_reset_init(void)
+int htif_system_reset_init(bool custom_base, unsigned long custom_base_addr)
 {
-	sbi_system_reset_add_device(&htif_reset);
+	int rc;
+
+	rc = set_custom_base(custom_base, custom_base_addr);
+	if (rc)
+		return rc;
 
+	sbi_system_reset_add_device(&htif_reset);
 	return 0;
 }
-- 
2.25.1