[PATCH v4 4/5] tty: Add SBI debug console support to HVC SBI driver

Anup Patel
2023-11-18T03:39:55Z

From: Atish Patra <atishp@rivosinc.com>

RISC-V SBI specification supports advanced debug console
support via SBI DBCN extension.

Extend the HVC SBI driver to support it.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
drivers/tty/hvc/Kconfig | 2 +-
drivers/tty/hvc/hvc_riscv_sbi.c | 59 +++++++++++++++++++++++++++++----
2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
index 4f9264d005c0..6e05c5c7bca1 100644
--- a/drivers/tty/hvc/Kconfig
+++ b/drivers/tty/hvc/Kconfig
@@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP

config HVC_RISCV_SBI
bool "RISC-V SBI console support"
- depends on RISCV_SBI_V01
+ depends on RISCV_SBI
select HVC_DRIVER
help
This enables support for console output via RISC-V SBI calls, which
diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
index 31f53fa77e4a..697c981221b5 100644
--- a/drivers/tty/hvc/hvc_riscv_sbi.c
+++ b/drivers/tty/hvc/hvc_riscv_sbi.c
@@ -39,21 +39,66 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
return i;
}

-static const struct hv_ops hvc_sbi_ops = {
+static const struct hv_ops hvc_sbi_v01_ops = {
.get_chars = hvc_sbi_tty_get,
.put_chars = hvc_sbi_tty_put,
};

-static int __init hvc_sbi_init(void)
+static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
{
- return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
+ phys_addr_t pa;
+
+ if (is_vmalloc_addr(buf)) {
+ pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
+ if (PAGE_SIZE < (offset_in_page(buf) + count))
+ count = PAGE_SIZE - offset_in_page(buf);
+ } else {
+ pa = __pa(buf);
+ }
+
+ return sbi_debug_console_write(count, pa);
}
-device_initcall(hvc_sbi_init);

-static int __init hvc_sbi_console_init(void)
+static int hvc_sbi_dbcn_tty_get(uint32_t vtermno, char *buf, int count)
{
- hvc_instantiate(0, 0, &hvc_sbi_ops);
+ phys_addr_t pa;
+
+ if (is_vmalloc_addr(buf)) {
+ pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
+ if (PAGE_SIZE < (offset_in_page(buf) + count))
+ count = PAGE_SIZE - offset_in_page(buf);
+ } else {
+ pa = __pa(buf);
+ }
+
+ return sbi_debug_console_read(count, pa);
+}
+
+static const struct hv_ops hvc_sbi_dbcn_ops = {
+ .put_chars = hvc_sbi_dbcn_tty_put,
+ .get_chars = hvc_sbi_dbcn_tty_get,
+};
+
+static int __init hvc_sbi_init(void)
+{
+ int err;
+
+ if (sbi_debug_console_available) {
+ err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_dbcn_ops, 256));
+ if (err)
+ return err;
+ hvc_instantiate(0, 0, &hvc_sbi_dbcn_ops);
+ } else {
+ if (IS_ENABLED(CONFIG_RISCV_SBI_V01)) {
+ err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_v01_ops, 256));
+ if (err)
+ return err;
+ hvc_instantiate(0, 0, &hvc_sbi_v01_ops);
+ } else {
+ return -ENODEV;
+ }
+ }

return 0;
}
-console_initcall(hvc_sbi_console_init);
+device_initcall(hvc_sbi_init);
--
2.34.1