* [PATCH 1/2] ARM: zte: Add support for zx29 low level debug
2026-05-13 21:34 [PATCH 0/2] amba/serial: amba-pl011: Bring back zx29 UART support Stefan Dösinger
@ 2026-05-13 21:34 ` Stefan Dösinger
2026-05-13 21:34 ` [PATCH 2/2] amba/serial: amba-pl011: Bring back zx29 UART support Stefan Dösinger
1 sibling, 0 replies; 3+ messages in thread
From: Stefan Dösinger @ 2026-05-13 21:34 UTC (permalink / raw)
To: Russell King, Greg Kroah-Hartman, Jiri Slaby
Cc: linux-arm-kernel, linux-kernel, linux-serial,
Stefan Dösinger, Linus Walleij
This is based on the removed zx29 code. A separate (more complicated)
patch will re-add the register map to the pl011 serial driver.
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Stefan Dösinger <stefandoesinger@gmail.com>
---
Patch changelog:
v8: Adjust UART01x_FR_BUSY to match the different ZX UART registers
(Sashiko). I am unsure about UART01x_FR_TXFF and my boards do not expose
flow control pins to allow me to test if it works.
I am unsure about the virtual address. It doesn't seem to matter, as
long as it is a valid address. This address is based on the old removed
code. Is there a rule-of-thumb physical to virtual mapping I can use to
give a sensible default value?
---
arch/arm/Kconfig.debug | 12 ++++++++++++
arch/arm/include/debug/pl01x.S | 9 +++++++++
2 files changed, 21 insertions(+)
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 366f162e147d..98d8a5a60048 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -1331,6 +1331,16 @@ choice
This option selects UART0 on VIA/Wondermedia System-on-a-chip
devices, including VT8500, WM8505, WM8650 and WM8850.
+ config DEBUG_ZTE_ZX
+ bool "Kernel low-level debugging via zx29 UART"
+ select DEBUG_UART_PL01X
+ depends on ARCH_ZTE
+ help
+ Say Y here if you are enabling ZTE zx297520v3 SOC and need
+ debug UART support. This UART is a PL011 with different
+ register addresses. The UART for boot messages on zx29 boards
+ is usually UART1 and is operating at 921600 8N1.
+
config DEBUG_ZYNQ_UART0
bool "Kernel low-level debugging on Xilinx Zynq using UART0"
depends on ARCH_ZYNQ
@@ -1545,6 +1555,7 @@ config DEBUG_UART_8250
config DEBUG_UART_PHYS
hex "Physical base address of debug UART"
+ default 0x01408000 if DEBUG_ZTE_ZX
default 0x01c28000 if DEBUG_SUNXI_UART0
default 0x01c28400 if DEBUG_SUNXI_UART1
default 0x01d0c000 if DEBUG_DAVINCI_DA8XX_UART1
@@ -1701,6 +1712,7 @@ config DEBUG_UART_VIRT
default 0xf31004c0 if DEBUG_MESON_UARTAO
default 0xf4090000 if DEBUG_LPC32XX
default 0xf4200000 if DEBUG_GEMINI
+ default 0xf4708000 if DEBUG_ZTE_ZX
default 0xf6200000 if DEBUG_PXA_UART1
default 0xf7000000 if DEBUG_SUN9I_UART0
default 0xf7000000 if DEBUG_S3C64XX_UART && DEBUG_S3C_UART0
diff --git a/arch/arm/include/debug/pl01x.S b/arch/arm/include/debug/pl01x.S
index c7e02d0628bf..9dcdeed2357d 100644
--- a/arch/arm/include/debug/pl01x.S
+++ b/arch/arm/include/debug/pl01x.S
@@ -8,6 +8,15 @@
*/
#include <linux/amba/serial.h>
+#ifdef CONFIG_DEBUG_ZTE_ZX
+#undef UART01x_DR
+#undef UART01x_FR
+#undef UART01x_FR_BUSY
+#define UART01x_DR 0x04
+#define UART01x_FR 0x14
+#define UART01x_FR_BUSY (1<<8)
+#endif
+
#ifdef CONFIG_DEBUG_UART_PHYS
.macro addruart, rp, rv, tmp
ldr \rp, =CONFIG_DEBUG_UART_PHYS
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/2] amba/serial: amba-pl011: Bring back zx29 UART support
2026-05-13 21:34 [PATCH 0/2] amba/serial: amba-pl011: Bring back zx29 UART support Stefan Dösinger
2026-05-13 21:34 ` [PATCH 1/2] ARM: zte: Add support for zx29 low level debug Stefan Dösinger
@ 2026-05-13 21:34 ` Stefan Dösinger
1 sibling, 0 replies; 3+ messages in thread
From: Stefan Dösinger @ 2026-05-13 21:34 UTC (permalink / raw)
To: Russell King, Greg Kroah-Hartman, Jiri Slaby
Cc: linux-arm-kernel, linux-kernel, linux-serial,
Stefan Dösinger, Linus Walleij
This is based on code removed in commit 89d4f98ae90d ("ARM: remove zte
zx platform"). I did not bring back the zx29-uart .compatible as the
arm,primecell-periphid does the job.
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Stefan Dösinger <stefandoesinger@gmail.com>
---
Changes since v4:
Use ZTE's JEDEC ID instead of 0xfe for the DT-Provided AMBA ID.
---
drivers/tty/serial/amba-pl011.c | 42 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 028e37ad8d79..8ed91e1da22b 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -240,6 +240,38 @@ static struct vendor_data vendor_nvidia = {
.get_fifosize = get_fifosize_nvidia,
};
+static const u16 pl011_zte_offsets[REG_ARRAY_SIZE] = {
+ [REG_DR] = ZX_UART011_DR,
+ [REG_FR] = ZX_UART011_FR,
+ [REG_LCRH_RX] = ZX_UART011_LCRH,
+ [REG_LCRH_TX] = ZX_UART011_LCRH,
+ [REG_IBRD] = ZX_UART011_IBRD,
+ [REG_FBRD] = ZX_UART011_FBRD,
+ [REG_CR] = ZX_UART011_CR,
+ [REG_IFLS] = ZX_UART011_IFLS,
+ [REG_IMSC] = ZX_UART011_IMSC,
+ [REG_RIS] = ZX_UART011_RIS,
+ [REG_MIS] = ZX_UART011_MIS,
+ [REG_ICR] = ZX_UART011_ICR,
+ [REG_DMACR] = ZX_UART011_DMACR,
+};
+
+static unsigned int get_fifosize_zte(struct amba_device *dev)
+{
+ return 16;
+}
+
+static struct vendor_data vendor_zte = {
+ .reg_offset = pl011_zte_offsets,
+ .access_32b = true,
+ .ifls = UART011_IFLS_RX4_8 | UART011_IFLS_TX4_8,
+ .fr_busy = ZX_UART01x_FR_BUSY,
+ .fr_dsr = ZX_UART01x_FR_DSR,
+ .fr_cts = ZX_UART01x_FR_CTS,
+ .fr_ri = ZX_UART011_FR_RI,
+ .get_fifosize = get_fifosize_zte,
+};
+
/* Deals with DMA transactions */
struct pl011_dmabuf {
@@ -3180,6 +3212,16 @@ static const struct amba_id pl011_ids[] = {
.mask = 0x000fffff,
.data = &vendor_nvidia,
},
+ {
+ /* This is an invented ID. The actual hardware that contains
+ * these ZTE UARTs (zx29 boards) has no AMBA PIDs stored. ZTE
+ * JEDEC ID (ignoring banks) and the "011" part number as used
+ * by ARM.
+ */
+ .id = 0x0008c011,
+ .mask = 0x000fffff,
+ .data = &vendor_zte,
+ },
{ 0, 0 },
};
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread