Subject: [PATCH v4 6/8] ARM: zte: Bring back zx29 UART support

From: Stefan Dösinger <[email-masked]>
Date: Thu, 16 Apr 2026 23:19:14 +0300

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.

Signed-off-by: Stefan Dösinger <[email-masked]>
---
 drivers/tty/serial/amba-pl011.c | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/amba/bus.h        |  6 ++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 7f17d288c807..858a0edd3e3b 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -216,6 +216,38 @@ static struct vendor_data vendor_st = {
 	.get_fifosize		= get_fifosize_st,
 };
 
+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 {
@@ -3081,6 +3113,11 @@ static const struct amba_id pl011_ids[] = {
 		.mask	= 0x00ffffff,
 		.data	= &vendor_st,
 	},
+	{
+		.id	= AMBA_LINUX_ID(0x00, 0x1, 0xffe),
+		.mask	= 0x00ffffff,
+		.data	= &vendor_zte,
+	},
 	{ 0, 0 },
 };
 
diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
index 9946276aff73..854c962d70f5 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -103,8 +103,14 @@ enum amba_vendor {
 	AMBA_VENDOR_ST = 0x80,
 	AMBA_VENDOR_QCOM = 0x51,
 	AMBA_VENDOR_LSI = 0xb6,
+	AMBA_VENDOR_LINUX = 0xfe,	/* This value is not official */
 };
 
+/* This is used to generate pseudo-ID for AMBA device */
+#define AMBA_LINUX_ID(conf, rev, part) \
+	(((conf) & 0xff) << 24 | ((rev) & 0xf) << 20 | \
+	AMBA_VENDOR_LINUX << 12 | ((part) & 0xfff))
+
 extern const struct bus_type amba_bustype;
 
 #define to_amba_device(d)	container_of_const(d, struct amba_device, dev)

-- 
2.52.0