[PATCH v5 2/5] RISC-V: Add SBI debug console helper routines

Anup Patel
2023-11-24T07:10:48Z

Let us provide SBI debug console helper routines which can be
shared by serial/earlycon-riscv-sbi.c and hvc/hvc_riscv_sbi.c.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
arch/riscv/include/asm/sbi.h | 5 +++
arch/riscv/kernel/sbi.c | 66 ++++++++++++++++++++++++++++++++++++
2 files changed, 71 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 66f3933c14f6..9eef25308d53 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -334,6 +334,11 @@ static inline unsigned long sbi_mk_version(unsigned long major,
}

int sbi_err_map_linux_errno(int err);
+
+extern bool sbi_debug_console_available;
+int sbi_debug_console_write(const char *bytes, unsigned int num_bytes);
+int sbi_debug_console_read(char *bytes, unsigned int num_bytes);
+
#else /* CONFIG_RISCV_SBI */
static inline int sbi_remote_fence_i(const struct cpumask *cpu_mask) { return -1; }
static inline void sbi_init(void) {}
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 5a62ed1da453..e66e0999a800 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -7,6 +7,7 @@

#include <linux/bits.h>
#include <linux/init.h>
+#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/reboot.h>
#include <asm/sbi.h>
@@ -571,6 +572,66 @@ long sbi_get_mimpid(void)
}
EXPORT_SYMBOL_GPL(sbi_get_mimpid);

+bool sbi_debug_console_available;
+
+int sbi_debug_console_write(const char *bytes, unsigned int num_bytes)
+{
+ phys_addr_t base_addr;
+ struct sbiret ret;
+
+ if (!sbi_debug_console_available)
+ return -EOPNOTSUPP;
+
+ if (is_vmalloc_addr(bytes))
+ base_addr = page_to_phys(vmalloc_to_page(bytes)) +
+ offset_in_page(bytes);
+ else
+ base_addr = __pa(bytes);
+ if (PAGE_SIZE < (offset_in_page(bytes) + num_bytes))
+ num_bytes = PAGE_SIZE - offset_in_page(bytes);
+
+ if (IS_ENABLED(CONFIG_32BIT))
+ ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
+ num_bytes, lower_32_bits(base_addr),
+ upper_32_bits(base_addr), 0, 0, 0);
+ else
+ ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
+ num_bytes, base_addr, 0, 0, 0, 0);
+
+ if (ret.error == SBI_ERR_FAILURE)
+ return -EIO;
+ return ret.error ? sbi_err_map_linux_errno(ret.error) : ret.value;
+}
+
+int sbi_debug_console_read(char *bytes, unsigned int num_bytes)
+{
+ phys_addr_t base_addr;
+ struct sbiret ret;
+
+ if (!sbi_debug_console_available)
+ return -EOPNOTSUPP;
+
+ if (is_vmalloc_addr(bytes))
+ base_addr = page_to_phys(vmalloc_to_page(bytes)) +
+ offset_in_page(bytes);
+ else
+ base_addr = __pa(bytes);
+ if (PAGE_SIZE < (offset_in_page(bytes) + num_bytes))
+ num_bytes = PAGE_SIZE - offset_in_page(bytes);
+
+ if (IS_ENABLED(CONFIG_32BIT))
+ ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
+ num_bytes, lower_32_bits(base_addr),
+ upper_32_bits(base_addr), 0, 0, 0);
+ else
+ ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
+ num_bytes, base_addr, 0, 0, 0, 0);
+
+ if (ret.error == SBI_ERR_FAILURE)
+ return -EIO;
+ return ret.error ? sbi_err_map_linux_errno(ret.error) : ret.value;
+}
+
void __init sbi_init(void)
{
int ret;
@@ -612,6 +673,11 @@ void __init sbi_init(void)
sbi_srst_reboot_nb.priority = 192;
register_restart_handler(&sbi_srst_reboot_nb);
}
+ if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
+ (sbi_probe_extension(SBI_EXT_DBCN) > 0)) {
+ pr_info("SBI DBCN extension detected\n");
+ sbi_debug_console_available = true;
+ }
} else {
__sbi_set_timer = __sbi_set_timer_v01;
__sbi_send_ipi = __sbi_send_ipi_v01;
--
2.34.1