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

[Atish Kumar Patra]

On Sun, Nov 19, 2023 at 11:16 PM Jiri Slaby  wrote:
>
> On 18. 11. 23, 4:38, Anup Patel wrote:
> > 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
> ...
> > -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, _sbi_ops);
> > + phys_addr_t pa;
> > +
> > + if (is_vmalloc_addr(buf)) {
>
> I wonder, where does this buf come from, so that you have to check for
> vmalloc?
>

When VMAP_STCK is enabled, stack allocation depends on the vmalloc.
That's why we have to if the buf is allocated using vmalloc.

> > + pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> > + if (PAGE_SIZE < (offset_in_page(buf) + count))
>
> Am I the only one who would prefer:
>if (count + offset_in_page(buf) > PAGE_SIZE)
> ?
>
> > + count = PAGE_SIZE - offset_in_page(buf);
> > + } else {
> > + pa = __pa(buf);
> > + }
> > +
> > + return sbi_debug_console_read(count, pa);
> > +}
>
>
> thanks,
> --
> js
> suse labs
>

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

[Jiri Slaby]

On 18. 11. 23, 4:38, Anup Patel wrote:

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

...

-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, _sbi_ops);
+   phys_addr_t pa;
+
+   if (is_vmalloc_addr(buf)) {


I wonder, where does this buf come from, so that you have to check for 
vmalloc?



+   pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
+   if (PAGE_SIZE < (offset_in_page(buf) + count))


Am I the only one who would prefer:
  if (count + offset_in_page(buf) > PAGE_SIZE)
?


+   count = PAGE_SIZE - offset_in_page(buf);
+   } else {
+   pa = __pa(buf);
+   }
+
+   return sbi_debug_console_read(count, pa);
+}



thanks,
--
js
suse labs

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

[Anup Patel]

From: Atish Patra 

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 
Signed-off-by: Anup Patel 
---
 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, _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, _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, _sbi_dbcn_ops, 256));
+   if (err)
+   return err;
+   hvc_instantiate(0, 0, _sbi_dbcn_ops);
+   } else {
+   if (IS_ENABLED(CONFIG_RISCV_SBI_V01)) {
+   err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, _sbi_v01_ops, 
256));
+   if (err)
+   return err;
+   hvc_instantiate(0, 0, _sbi_v01_ops);
+   } else {
+   return -ENODEV;
+   }
+   }
 
return 0;
 }
-console_initcall(hvc_sbi_console_init);
+device_initcall(hvc_sbi_init);
-- 
2.34.1