On Fri, Oct 20, 2023 at 3:25 PM Björn Töpel [off-list ref] wrote:

Anup Patel [off-list ref] writes:

quoted

From: Atish Patra <redacted>

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 <redacted>
Signed-off-by: Anup Patel <redacted>
---
 drivers/tty/hvc/Kconfig         |  2 +-
 drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
 2 files changed, 76 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..56da1a4b5aca 100644
--- a/drivers/tty/hvc/hvc_riscv_sbi.c
+++ b/drivers/tty/hvc/hvc_riscv_sbi.c

@@ -39,21 +39,89 @@ 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;
+     struct sbiret ret;
+
+     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);

Thanks for fixing the cross-page issue. Now you're cutting the buffer
off. What about doing two SBI calls instead? (Dito on the get side)

We don't need to handle that because the hvc_console framework
will ensure remaining characters are sent-out. Same applies to
get side as well.

Regards,
Anup