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

[Anup Patel]

From: Atish Patra <ati...@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 <ati...@rivosinc.com>
Signed-off-by: Anup Patel <apa...@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