[PATCH v3 0/3] Complete ZTE PL011 device support

[PATCH v3 0/3] Complete ZTE PL011 device support

[Shawn Guo]

This is a pick-up of Jun's v2 patch which tries to complete ZTE PL011
support.

Commit 7ec758718920 ("tty: amba-pl011: add support for ZTE UART
(EXPERIMENTAL)") from Russell had already done part of the work that is
needed for ZTE PL011 support.  The series adds the missing pieces which
includes handling Flag Register bit position oddness and getting ZTE
PL011 device probed by amba-pl011 driver.

Thanks to Russell for the "official" pseudo-ID idea.

Changes since v2:
 - Split changes into 3 separate patches
 - Take Russell's suggestion using helper macro to create pseudo-ID
 - Rebase to v4.7-rc6

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-March/417192.html

Shawn Guo (3):
  tty: amba-pl011: define flag register bits for ZTE device
  tty: amba-pl011: add .get_fifosize for ZTE device
  tty: amba-pl011: probe ZTE device from AMBA bus with a pseudo-ID

 drivers/tty/serial/amba-pl011.c | 59 ++++++++++++++++++++++++++++++++---------
 include/linux/amba/bus.h        |  6 +++++
 include/linux/amba/serial.h     |  9 +++++++
 3 files changed, 62 insertions(+), 12 deletions(-)

-- 
1.9.1

[PATCH v3 0/3] Complete ZTE PL011 device support

[Shawn Guo]

This is a pick-up of Jun's v2 patch which tries to complete ZTE PL011
support.

Commit 7ec758718920 ("tty: amba-pl011: add support for ZTE UART
(EXPERIMENTAL)") from Russell had already done part of the work that is
needed for ZTE PL011 support.  The series adds the missing pieces which
includes handling Flag Register bit position oddness and getting ZTE
PL011 device probed by amba-pl011 driver.

Thanks to Russell for the "official" pseudo-ID idea.

Changes since v2:
 - Split changes into 3 separate patches
 - Take Russell's suggestion using helper macro to create pseudo-ID
 - Rebase to v4.7-rc6

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-March/417192.html

Shawn Guo (3):
  tty: amba-pl011: define flag register bits for ZTE device
  tty: amba-pl011: add .get_fifosize for ZTE device
  tty: amba-pl011: probe ZTE device from AMBA bus with a pseudo-ID

 drivers/tty/serial/amba-pl011.c | 59 ++++++++++++++++++++++++++++++++---------
 include/linux/amba/bus.h        |  6 +++++
 include/linux/amba/serial.h     |  9 +++++++
 3 files changed, 62 insertions(+), 12 deletions(-)

-- 
1.9.1

[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Shawn Guo]

For some reason we do not really understand, ZTE hardware designers
choose to define PL011 Flag Register bit positions differently from
standard ones as below.

	Bit		Standard	ZTE
	-----------------------------------
	CTS		0		1
	DSR		1		3
	BUSY		3		8
	RI		8		0

Let's define these bits into vendor data and get ZTE PL011 supported
properly.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/tty/serial/amba-pl011.c | 45 ++++++++++++++++++++++++++++++++---------
 include/linux/amba/serial.h     |  9 +++++++++
 2 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 1b7331e40d79..e09354e6bcb7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -93,6 +93,10 @@ static u16 pl011_std_offsets[REG_ARRAY_SIZE] = {
 struct vendor_data {
 	const u16		*reg_offset;
 	unsigned int		ifls;
+	unsigned int		fr_busy;
+	unsigned int		fr_dsr;
+	unsigned int		fr_cts;
+	unsigned int		fr_ri;
 	bool			access_32b;
 	bool			oversampling;
 	bool			dma_threshold;
@@ -111,6 +115,10 @@ static unsigned int get_fifosize_arm(struct amba_device *dev)
 static struct vendor_data vendor_arm = {
 	.reg_offset		= pl011_std_offsets,
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.oversampling		= false,
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
@@ -121,6 +129,10 @@ static struct vendor_data vendor_arm = {
 
 static struct vendor_data vendor_sbsa = {
 	.reg_offset		= pl011_std_offsets,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.access_32b		= true,
 	.oversampling		= false,
 	.dma_threshold		= false,
@@ -164,6 +176,10 @@ static unsigned int get_fifosize_st(struct amba_device *dev)
 static struct vendor_data vendor_st = {
 	.reg_offset		= pl011_st_offsets,
 	.ifls			= UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.oversampling		= true,
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
@@ -192,6 +208,10 @@ static struct vendor_data vendor_zte __maybe_unused = {
 	.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_arm,
 };
 
@@ -1167,7 +1187,7 @@ static void pl011_dma_shutdown(struct uart_amba_port *uap)
 		return;
 
 	/* Disable RX and TX DMA */
-	while (pl011_read(uap, REG_FR) & UART01x_FR_BUSY)
+	while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 
 	spin_lock_irq(&uap->port.lock);
@@ -1416,11 +1436,12 @@ static void pl011_modem_status(struct uart_amba_port *uap)
 	if (delta & UART01x_FR_DCD)
 		uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
 
-	if (delta & UART01x_FR_DSR)
+	if (delta & uap->vendor->fr_dsr)
 		uap->port.icount.dsr++;
 
-	if (delta & UART01x_FR_CTS)
-		uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
+	if (delta & uap->vendor->fr_cts)
+		uart_handle_cts_change(&uap->port,
+				       status & uap->vendor->fr_cts);
 
 	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
 }
@@ -1493,7 +1514,8 @@ static unsigned int pl011_tx_empty(struct uart_port *port)
 	struct uart_amba_port *uap =
 	    container_of(port, struct uart_amba_port, port);
 	unsigned int status = pl011_read(uap, REG_FR);
-	return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
+	return status & (uap->vendor->fr_busy | UART01x_FR_TXFF) ?
+							0 : TIOCSER_TEMT;
 }
 
 static unsigned int pl011_get_mctrl(struct uart_port *port)
@@ -1508,9 +1530,9 @@ static unsigned int pl011_get_mctrl(struct uart_port *port)
 		result |= tiocmbit
 
 	TIOCMBIT(UART01x_FR_DCD, TIOCM_CAR);
-	TIOCMBIT(UART01x_FR_DSR, TIOCM_DSR);
-	TIOCMBIT(UART01x_FR_CTS, TIOCM_CTS);
-	TIOCMBIT(UART011_FR_RI, TIOCM_RNG);
+	TIOCMBIT(uap->vendor->fr_dsr, TIOCM_DSR);
+	TIOCMBIT(uap->vendor->fr_cts, TIOCM_CTS);
+	TIOCMBIT(uap->vendor->fr_ri, TIOCM_RNG);
 #undef TIOCMBIT
 	return result;
 }
@@ -2191,7 +2213,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 	 *	Finally, wait for transmitter to become empty
 	 *	and restore the TCR
 	 */
-	while (pl011_read(uap, REG_FR) & UART01x_FR_BUSY)
+	while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 	if (!uap->vendor->always_enabled)
 		pl011_write(old_cr, uap, REG_CR);
@@ -2303,13 +2325,16 @@ static struct console amba_console = {
 
 static void pl011_putc(struct uart_port *port, int c)
 {
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
 		cpu_relax();
 	if (port->iotype == UPIO_MEM32)
 		writel(c, port->membase + UART01x_DR);
 	else
 		writeb(c, port->membase + UART01x_DR);
-	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
+	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 }
 
diff --git a/include/linux/amba/serial.h b/include/linux/amba/serial.h
index d76a19ba2cff..ad0965e21a5e 100644
--- a/include/linux/amba/serial.h
+++ b/include/linux/amba/serial.h
@@ -104,6 +104,15 @@
 #define UART01x_FR_CTS 		0x001
 #define UART01x_FR_TMSK		(UART01x_FR_TXFF + UART01x_FR_BUSY)
 
+/*
+ * Some bits of Flag Register on ZTE device have different position from
+ * standard ones.
+ */
+#define ZX_UART01x_FR_BUSY	0x100
+#define ZX_UART01x_FR_DSR	0x008
+#define ZX_UART01x_FR_CTS	0x002
+#define ZX_UART011_FR_RI	0x001
+
 #define UART011_CR_CTSEN	0x8000	/* CTS hardware flow control */
 #define UART011_CR_RTSEN	0x4000	/* RTS hardware flow control */
 #define UART011_CR_OUT2		0x2000	/* OUT2 */
-- 
1.9.1

[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Shawn Guo]

For some reason we do not really understand, ZTE hardware designers
choose to define PL011 Flag Register bit positions differently from
standard ones as below.

	Bit		Standard	ZTE
	-----------------------------------
	CTS		0		1
	DSR		1		3
	BUSY		3		8
	RI		8		0

Let's define these bits into vendor data and get ZTE PL011 supported
properly.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/tty/serial/amba-pl011.c | 45 ++++++++++++++++++++++++++++++++---------
 include/linux/amba/serial.h     |  9 +++++++++
 2 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 1b7331e40d79..e09354e6bcb7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -93,6 +93,10 @@ static u16 pl011_std_offsets[REG_ARRAY_SIZE] = {
 struct vendor_data {
 	const u16		*reg_offset;
 	unsigned int		ifls;
+	unsigned int		fr_busy;
+	unsigned int		fr_dsr;
+	unsigned int		fr_cts;
+	unsigned int		fr_ri;
 	bool			access_32b;
 	bool			oversampling;
 	bool			dma_threshold;
@@ -111,6 +115,10 @@ static unsigned int get_fifosize_arm(struct amba_device *dev)
 static struct vendor_data vendor_arm = {
 	.reg_offset		= pl011_std_offsets,
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.oversampling		= false,
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
@@ -121,6 +129,10 @@ static struct vendor_data vendor_arm = {
 
 static struct vendor_data vendor_sbsa = {
 	.reg_offset		= pl011_std_offsets,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.access_32b		= true,
 	.oversampling		= false,
 	.dma_threshold		= false,
@@ -164,6 +176,10 @@ static unsigned int get_fifosize_st(struct amba_device *dev)
 static struct vendor_data vendor_st = {
 	.reg_offset		= pl011_st_offsets,
 	.ifls			= UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.oversampling		= true,
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
@@ -192,6 +208,10 @@ static struct vendor_data vendor_zte __maybe_unused = {
 	.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_arm,
 };
 
@@ -1167,7 +1187,7 @@ static void pl011_dma_shutdown(struct uart_amba_port *uap)
 		return;
 
 	/* Disable RX and TX DMA */
-	while (pl011_read(uap, REG_FR) & UART01x_FR_BUSY)
+	while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 
 	spin_lock_irq(&uap->port.lock);
@@ -1416,11 +1436,12 @@ static void pl011_modem_status(struct uart_amba_port *uap)
 	if (delta & UART01x_FR_DCD)
 		uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
 
-	if (delta & UART01x_FR_DSR)
+	if (delta & uap->vendor->fr_dsr)
 		uap->port.icount.dsr++;
 
-	if (delta & UART01x_FR_CTS)
-		uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
+	if (delta & uap->vendor->fr_cts)
+		uart_handle_cts_change(&uap->port,
+				       status & uap->vendor->fr_cts);
 
 	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
 }
@@ -1493,7 +1514,8 @@ static unsigned int pl011_tx_empty(struct uart_port *port)
 	struct uart_amba_port *uap =
 	    container_of(port, struct uart_amba_port, port);
 	unsigned int status = pl011_read(uap, REG_FR);
-	return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
+	return status & (uap->vendor->fr_busy | UART01x_FR_TXFF) ?
+							0 : TIOCSER_TEMT;
 }
 
 static unsigned int pl011_get_mctrl(struct uart_port *port)
@@ -1508,9 +1530,9 @@ static unsigned int pl011_get_mctrl(struct uart_port *port)
 		result |= tiocmbit
 
 	TIOCMBIT(UART01x_FR_DCD, TIOCM_CAR);
-	TIOCMBIT(UART01x_FR_DSR, TIOCM_DSR);
-	TIOCMBIT(UART01x_FR_CTS, TIOCM_CTS);
-	TIOCMBIT(UART011_FR_RI, TIOCM_RNG);
+	TIOCMBIT(uap->vendor->fr_dsr, TIOCM_DSR);
+	TIOCMBIT(uap->vendor->fr_cts, TIOCM_CTS);
+	TIOCMBIT(uap->vendor->fr_ri, TIOCM_RNG);
 #undef TIOCMBIT
 	return result;
 }
@@ -2191,7 +2213,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 	 *	Finally, wait for transmitter to become empty
 	 *	and restore the TCR
 	 */
-	while (pl011_read(uap, REG_FR) & UART01x_FR_BUSY)
+	while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 	if (!uap->vendor->always_enabled)
 		pl011_write(old_cr, uap, REG_CR);
@@ -2303,13 +2325,16 @@ static struct console amba_console = {
 
 static void pl011_putc(struct uart_port *port, int c)
 {
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
 		cpu_relax();
 	if (port->iotype == UPIO_MEM32)
 		writel(c, port->membase + UART01x_DR);
 	else
 		writeb(c, port->membase + UART01x_DR);
-	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
+	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 }
 
diff --git a/include/linux/amba/serial.h b/include/linux/amba/serial.h
index d76a19ba2cff..ad0965e21a5e 100644
--- a/include/linux/amba/serial.h
+++ b/include/linux/amba/serial.h
@@ -104,6 +104,15 @@
 #define UART01x_FR_CTS 		0x001
 #define UART01x_FR_TMSK		(UART01x_FR_TXFF + UART01x_FR_BUSY)
 
+/*
+ * Some bits of Flag Register on ZTE device have different position from
+ * standard ones.
+ */
+#define ZX_UART01x_FR_BUSY	0x100
+#define ZX_UART01x_FR_DSR	0x008
+#define ZX_UART01x_FR_CTS	0x002
+#define ZX_UART011_FR_RI	0x001
+
 #define UART011_CR_CTSEN	0x8000	/* CTS hardware flow control */
 #define UART011_CR_RTSEN	0x4000	/* RTS hardware flow control */
 #define UART011_CR_OUT2		0x2000	/* OUT2 */
-- 
1.9.1

[PATCH v3 2/3] tty: amba-pl011: add .get_fifosize for ZTE device

[Shawn Guo]

ZTE PL011 device has a fixed FIFO size 16.  Let's add a .get_fifosize
hook for it.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/tty/serial/amba-pl011.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index e09354e6bcb7..8b7fb3689ee7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -204,6 +204,11 @@ static const u16 pl011_zte_offsets[REG_ARRAY_SIZE] = {
 	[REG_DMACR] = ZX_UART011_DMACR,
 };
 
+static unsigned int get_fifosize_zte(struct amba_device *dev)
+{
+	return 16;
+}
+
 static struct vendor_data vendor_zte __maybe_unused = {
 	.reg_offset		= pl011_zte_offsets,
 	.access_32b		= true,
@@ -212,7 +217,7 @@ static struct vendor_data vendor_zte __maybe_unused = {
 	.fr_dsr			= ZX_UART01x_FR_DSR,
 	.fr_cts			= ZX_UART01x_FR_CTS,
 	.fr_ri			= ZX_UART011_FR_RI,
-	.get_fifosize		= get_fifosize_arm,
+	.get_fifosize		= get_fifosize_zte,
 };
 
 /* Deals with DMA transactions */
-- 
1.9.1

[PATCH v3 2/3] tty: amba-pl011: add .get_fifosize for ZTE device

[Shawn Guo]

ZTE PL011 device has a fixed FIFO size 16.  Let's add a .get_fifosize
hook for it.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/tty/serial/amba-pl011.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index e09354e6bcb7..8b7fb3689ee7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -204,6 +204,11 @@ static const u16 pl011_zte_offsets[REG_ARRAY_SIZE] = {
 	[REG_DMACR] = ZX_UART011_DMACR,
 };
 
+static unsigned int get_fifosize_zte(struct amba_device *dev)
+{
+	return 16;
+}
+
 static struct vendor_data vendor_zte __maybe_unused = {
 	.reg_offset		= pl011_zte_offsets,
 	.access_32b		= true,
@@ -212,7 +217,7 @@ static struct vendor_data vendor_zte __maybe_unused = {
 	.fr_dsr			= ZX_UART01x_FR_DSR,
 	.fr_cts			= ZX_UART01x_FR_CTS,
 	.fr_ri			= ZX_UART011_FR_RI,
-	.get_fifosize		= get_fifosize_arm,
+	.get_fifosize		= get_fifosize_zte,
 };
 
 /* Deals with DMA transactions */
-- 
1.9.1

[PATCH v3 3/3] tty: amba-pl011: probe ZTE device from AMBA bus with a pseudo-ID

[Shawn Guo]

There is no Peripheral Identification Registers on ZTE PL011 device, so
although the driver amba-pl011 is ready to work for ZTE device, the
device cannot be probed by the driver at all.

With arm,primecell-periphid DT bindings (bindings/arm/primecell.txt) in
place, it should be the cleanest the way to use a pseudo-ID to probe the
device from AMBA bus.  We create an unofficial vendor number
AMBA_VENDOR_LINUX, which will practically never become an official
vendor ID, and takes Configuration, Revision number, and Part number as
input to compose a pseudo-ID for ZTE device.

Also, since we start using vendor_zte to probe ZTE device, the
__maybe_unused for vendor_zte is removed.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/tty/serial/amba-pl011.c | 7 ++++++-
 include/linux/amba/bus.h        | 6 ++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8b7fb3689ee7..6b349af7fadf 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -209,7 +209,7 @@ static unsigned int get_fifosize_zte(struct amba_device *dev)
 	return 16;
 }
 
-static struct vendor_data vendor_zte __maybe_unused = {
+static struct vendor_data vendor_zte = {
 	.reg_offset		= pl011_zte_offsets,
 	.access_32b		= true,
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
@@ -2646,6 +2646,11 @@ static 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 3d8dcdd1aeae..d143c13bed26 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -53,8 +53,14 @@ 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 struct bus_type amba_bustype;
 
 #define to_amba_device(d)	container_of(d, struct amba_device, dev)
-- 
1.9.1

[PATCH v3 3/3] tty: amba-pl011: probe ZTE device from AMBA bus with a pseudo-ID

[Shawn Guo]

There is no Peripheral Identification Registers on ZTE PL011 device, so
although the driver amba-pl011 is ready to work for ZTE device, the
device cannot be probed by the driver at all.

With arm,primecell-periphid DT bindings (bindings/arm/primecell.txt) in
place, it should be the cleanest the way to use a pseudo-ID to probe the
device from AMBA bus.  We create an unofficial vendor number
AMBA_VENDOR_LINUX, which will practically never become an official
vendor ID, and takes Configuration, Revision number, and Part number as
input to compose a pseudo-ID for ZTE device.

Also, since we start using vendor_zte to probe ZTE device, the
__maybe_unused for vendor_zte is removed.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 drivers/tty/serial/amba-pl011.c | 7 ++++++-
 include/linux/amba/bus.h        | 6 ++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8b7fb3689ee7..6b349af7fadf 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -209,7 +209,7 @@ static unsigned int get_fifosize_zte(struct amba_device *dev)
 	return 16;
 }
 
-static struct vendor_data vendor_zte __maybe_unused = {
+static struct vendor_data vendor_zte = {
 	.reg_offset		= pl011_zte_offsets,
 	.access_32b		= true,
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
@@ -2646,6 +2646,11 @@ static 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 3d8dcdd1aeae..d143c13bed26 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -53,8 +53,14 @@ 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 struct bus_type amba_bustype;
 
 #define to_amba_device(d)	container_of(d, struct amba_device, dev)
-- 
1.9.1

Re: [PATCH v3 0/3] Complete ZTE PL011 device support

[Shawn Guo]

On Fri, Jul 08, 2016 at 05:00:38PM +0800, Shawn Guo wrote:
> This is a pick-up of Jun's v2 patch which tries to complete ZTE PL011
> support.
> 
> Commit 7ec758718920 ("tty: amba-pl011: add support for ZTE UART
> (EXPERIMENTAL)") from Russell had already done part of the work that is
> needed for ZTE PL011 support.  The series adds the missing pieces which
> includes handling Flag Register bit position oddness and getting ZTE
> PL011 device probed by amba-pl011 driver.
> 
> Thanks to Russell for the "official" pseudo-ID idea.
> 
> Changes since v2:
>  - Split changes into 3 separate patches
>  - Take Russell's suggestion using helper macro to create pseudo-ID
>  - Rebase to v4.7-rc6
> 
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-March/417192.html
> 
> Shawn Guo (3):
>   tty: amba-pl011: define flag register bits for ZTE device
>   tty: amba-pl011: add .get_fifosize for ZTE device
>   tty: amba-pl011: probe ZTE device from AMBA bus with a pseudo-ID

Hi Russell,

Most of the changes of patch #3 are yours, so presumably you are fine
with it.  What about #1 and #2?  May I have your ACK on them, so that I
can ask Greg to pick up the series?  Thanks.

Shawn

[PATCH v3 0/3] Complete ZTE PL011 device support

[Shawn Guo]

On Fri, Jul 08, 2016 at 05:00:38PM +0800, Shawn Guo wrote:
> This is a pick-up of Jun's v2 patch which tries to complete ZTE PL011
> support.
> 
> Commit 7ec758718920 ("tty: amba-pl011: add support for ZTE UART
> (EXPERIMENTAL)") from Russell had already done part of the work that is
> needed for ZTE PL011 support.  The series adds the missing pieces which
> includes handling Flag Register bit position oddness and getting ZTE
> PL011 device probed by amba-pl011 driver.
> 
> Thanks to Russell for the "official" pseudo-ID idea.
> 
> Changes since v2:
>  - Split changes into 3 separate patches
>  - Take Russell's suggestion using helper macro to create pseudo-ID
>  - Rebase to v4.7-rc6
> 
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-March/417192.html
> 
> Shawn Guo (3):
>   tty: amba-pl011: define flag register bits for ZTE device
>   tty: amba-pl011: add .get_fifosize for ZTE device
>   tty: amba-pl011: probe ZTE device from AMBA bus with a pseudo-ID

Hi Russell,

Most of the changes of patch #3 are yours, so presumably you are fine
with it.  What about #1 and #2?  May I have your ACK on them, so that I
can ask Greg to pick up the series?  Thanks.

Shawn

Re: [PATCH v3 0/3] Complete ZTE PL011 device support

[Russell King - ARM Linux]

On Thu, Jul 14, 2016 at 09:26:20PM +0800, Shawn Guo wrote:
> Most of the changes of patch #3 are yours, so presumably you are fine
> with it.  What about #1 and #2?  May I have your ACK on them, so that I
> can ask Greg to pick up the series?  Thanks.

Yes, the three patches look fine.  For the first two:

Acked-by: Russell King <rmk+kernel@armlinux.org.uk>

Thanks.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

[PATCH v3 0/3] Complete ZTE PL011 device support

[Russell King - ARM Linux]

On Thu, Jul 14, 2016 at 09:26:20PM +0800, Shawn Guo wrote:
> Most of the changes of patch #3 are yours, so presumably you are fine
> with it.  What about #1 and #2?  May I have your ACK on them, so that I
> can ask Greg to pick up the series?  Thanks.

Yes, the three patches look fine.  For the first two:

Acked-by: Russell King <rmk+kernel@armlinux.org.uk>

Thanks.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

Re: [PATCH v3 0/3] Complete ZTE PL011 device support

[Shawn Guo]

On Mon, Jul 18, 2016 at 02:35:16PM +0100, Russell King - ARM Linux wrote:
> On Thu, Jul 14, 2016 at 09:26:20PM +0800, Shawn Guo wrote:
> > Most of the changes of patch #3 are yours, so presumably you are fine
> > with it.  What about #1 and #2?  May I have your ACK on them, so that I
> > can ask Greg to pick up the series?  Thanks.
> 
> Yes, the three patches look fine.  For the first two:
> 
> Acked-by: Russell King <rmk+kernel@armlinux.org.uk>

Hi Greg,

The series missed 4.8 merge window.  Since v4.8-rc1 is out there, can
you please queue the it up for the next?  The series can still apply
on v4.8-rc1 cleanly.  Thanks.

Shawn

[PATCH v3 0/3] Complete ZTE PL011 device support

[Shawn Guo]

On Mon, Jul 18, 2016 at 02:35:16PM +0100, Russell King - ARM Linux wrote:
> On Thu, Jul 14, 2016 at 09:26:20PM +0800, Shawn Guo wrote:
> > Most of the changes of patch #3 are yours, so presumably you are fine
> > with it.  What about #1 and #2?  May I have your ACK on them, so that I
> > can ask Greg to pick up the series?  Thanks.
> 
> Yes, the three patches look fine.  For the first two:
> 
> Acked-by: Russell King <rmk+kernel@armlinux.org.uk>

Hi Greg,

The series missed 4.8 merge window.  Since v4.8-rc1 is out there, can
you please queue the it up for the next?  The series can still apply
on v4.8-rc1 cleanly.  Thanks.

Shawn

Re: [PATCH v3 0/3] Complete ZTE PL011 device support

[Greg Kroah-Hartman]

On Tue, Aug 09, 2016 at 11:21:53AM +0800, Shawn Guo wrote:
> On Mon, Jul 18, 2016 at 02:35:16PM +0100, Russell King - ARM Linux wrote:
> > On Thu, Jul 14, 2016 at 09:26:20PM +0800, Shawn Guo wrote:
> > > Most of the changes of patch #3 are yours, so presumably you are fine
> > > with it.  What about #1 and #2?  May I have your ACK on them, so that I
> > > can ask Greg to pick up the series?  Thanks.
> > 
> > Yes, the three patches look fine.  For the first two:
> > 
> > Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
> 
> Hi Greg,
> 
> The series missed 4.8 merge window.  Since v4.8-rc1 is out there, can
> you please queue the it up for the next?  The series can still apply
> on v4.8-rc1 cleanly.  Thanks.

Yes, it's in my queue, I will get to it "soon".

thanks,

greg k-h

[PATCH v3 0/3] Complete ZTE PL011 device support

[Greg Kroah-Hartman]

On Tue, Aug 09, 2016 at 11:21:53AM +0800, Shawn Guo wrote:
> On Mon, Jul 18, 2016 at 02:35:16PM +0100, Russell King - ARM Linux wrote:
> > On Thu, Jul 14, 2016 at 09:26:20PM +0800, Shawn Guo wrote:
> > > Most of the changes of patch #3 are yours, so presumably you are fine
> > > with it.  What about #1 and #2?  May I have your ACK on them, so that I
> > > can ask Greg to pick up the series?  Thanks.
> > 
> > Yes, the three patches look fine.  For the first two:
> > 
> > Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
> 
> Hi Greg,
> 
> The series missed 4.8 merge window.  Since v4.8-rc1 is out there, can
> you please queue the it up for the next?  The series can still apply
> on v4.8-rc1 cleanly.  Thanks.

Yes, it's in my queue, I will get to it "soon".

thanks,

greg k-h

Re: [PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Sudeep Holla]

Hi Shawn, Russell,

I noticed this change is in linux-next and but I happen to hit an issue
with this as I tested it with earlycon enabled today for the first time.

On 08/07/16 10:00, Shawn Guo wrote:
> For some reason we do not really understand, ZTE hardware designers
> choose to define PL011 Flag Register bit positions differently from
> standard ones as below.
>
> 	Bit		Standard	ZTE
> 	-----------------------------------
> 	CTS		0		1
> 	DSR		1		3
> 	BUSY		3		8
> 	RI		8		0
>
> Let's define these bits into vendor data and get ZTE PL011 supported
> properly.
>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

[...]

> @@ -2303,13 +2325,16 @@ static struct console amba_console = {
>
>  static void pl011_putc(struct uart_port *port, int c)
>  {
> +	struct uart_amba_port *uap =
> +		container_of(port, struct uart_amba_port, port);
> +
>  	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
>  		cpu_relax();
>  	if (port->iotype == UPIO_MEM32)
>  		writel(c, port->membase + UART01x_DR);
>  	else
>  		writeb(c, port->membase + UART01x_DR);
> -	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> +	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
>  		cpu_relax();
>  }

The above hunk won't work for early console devices. The earlycon_device
just has uart_port and is not uart_amba_port. I don't know how to fix
this properly but I thought we could reuse private_data in uart_port for
early_con devices. Something like below(incomplete for other vendors,
works only for ARM)

Regards,
Sudeep

-->8

diff --git i/drivers/tty/serial/amba-pl011.c 
w/drivers/tty/serial/amba-pl011.c
index 0b78b04e895e..abe88223790c 100644
--- i/drivers/tty/serial/amba-pl011.c
+++ w/drivers/tty/serial/amba-pl011.c
@@ -2330,8 +2330,7 @@ static struct console amba_console = {

  static void pl011_putc(struct uart_port *port, int c)
  {
-       struct uart_amba_port *uap =
-               container_of(port, struct uart_amba_port, port);
+       struct vendor_data *vendor = port->private_data;

         while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
                 cpu_relax();
@@ -2339,7 +2338,7 @@ static void pl011_putc(struct uart_port *port, int c)
                 writel(c, port->membase + UART01x_DR);
         else
                 writeb(c, port->membase + UART01x_DR);
-       while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
+       while (readl(port->membase + UART01x_FR) & vendor->fr_busy)
                 cpu_relax();
  }

@@ -2356,6 +2355,7 @@ static int __init pl011_early_console_setup(struct 
earlycon_device *device,
         if (!device->port.membase)
                 return -ENODEV;

+       device->port.private_data = &vendor_arm;
         device->con->write = pl011_early_write;
         return 0;
  }

[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Sudeep Holla]

Hi Shawn, Russell,

I noticed this change is in linux-next and but I happen to hit an issue
with this as I tested it with earlycon enabled today for the first time.

On 08/07/16 10:00, Shawn Guo wrote:
> For some reason we do not really understand, ZTE hardware designers
> choose to define PL011 Flag Register bit positions differently from
> standard ones as below.
>
> 	Bit		Standard	ZTE
> 	-----------------------------------
> 	CTS		0		1
> 	DSR		1		3
> 	BUSY		3		8
> 	RI		8		0
>
> Let's define these bits into vendor data and get ZTE PL011 supported
> properly.
>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

[...]

> @@ -2303,13 +2325,16 @@ static struct console amba_console = {
>
>  static void pl011_putc(struct uart_port *port, int c)
>  {
> +	struct uart_amba_port *uap =
> +		container_of(port, struct uart_amba_port, port);
> +
>  	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
>  		cpu_relax();
>  	if (port->iotype == UPIO_MEM32)
>  		writel(c, port->membase + UART01x_DR);
>  	else
>  		writeb(c, port->membase + UART01x_DR);
> -	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> +	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
>  		cpu_relax();
>  }

The above hunk won't work for early console devices. The earlycon_device
just has uart_port and is not uart_amba_port. I don't know how to fix
this properly but I thought we could reuse private_data in uart_port for
early_con devices. Something like below(incomplete for other vendors,
works only for ARM)

Regards,
Sudeep

-->8

diff --git i/drivers/tty/serial/amba-pl011.c 
w/drivers/tty/serial/amba-pl011.c
index 0b78b04e895e..abe88223790c 100644
--- i/drivers/tty/serial/amba-pl011.c
+++ w/drivers/tty/serial/amba-pl011.c
@@ -2330,8 +2330,7 @@ static struct console amba_console = {

  static void pl011_putc(struct uart_port *port, int c)
  {
-       struct uart_amba_port *uap =
-               container_of(port, struct uart_amba_port, port);
+       struct vendor_data *vendor = port->private_data;

         while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
                 cpu_relax();
@@ -2339,7 +2338,7 @@ static void pl011_putc(struct uart_port *port, int c)
                 writel(c, port->membase + UART01x_DR);
         else
                 writeb(c, port->membase + UART01x_DR);
-       while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
+       while (readl(port->membase + UART01x_FR) & vendor->fr_busy)
                 cpu_relax();
  }

@@ -2356,6 +2355,7 @@ static int __init pl011_early_console_setup(struct 
earlycon_device *device,
         if (!device->port.membase)
                 return -ENODEV;

+       device->port.private_data = &vendor_arm;
         device->con->write = pl011_early_write;
         return 0;
  }

Re: [PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Russell King - ARM Linux]

On Fri, Sep 16, 2016 at 03:23:57PM +0100, Sudeep Holla wrote:
> Hi Shawn, Russell,
> 
> I noticed this change is in linux-next and but I happen to hit an issue
> with this as I tested it with earlycon enabled today for the first time.
> 
> On 08/07/16 10:00, Shawn Guo wrote:
> >For some reason we do not really understand, ZTE hardware designers
> >choose to define PL011 Flag Register bit positions differently from
> >standard ones as below.
> >
> >	Bit		Standard	ZTE
> >	-----------------------------------
> >	CTS		0		1
> >	DSR		1		3
> >	BUSY		3		8
> >	RI		8		0
> >
> >Let's define these bits into vendor data and get ZTE PL011 supported
> >properly.
> >
> >Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> 
> [...]
> 
> >@@ -2303,13 +2325,16 @@ static struct console amba_console = {
> >
> > static void pl011_putc(struct uart_port *port, int c)
> > {
> >+	struct uart_amba_port *uap =
> >+		container_of(port, struct uart_amba_port, port);
> >+
> > 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> > 		cpu_relax();
> > 	if (port->iotype == UPIO_MEM32)
> > 		writel(c, port->membase + UART01x_DR);
> > 	else
> > 		writeb(c, port->membase + UART01x_DR);
> >-	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> >+	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
> > 		cpu_relax();
> > }
> 
> The above hunk won't work for early console devices. The earlycon_device
> just has uart_port and is not uart_amba_port. I don't know how to fix
> this properly but I thought we could reuse private_data in uart_port for
> early_con devices. Something like below(incomplete for other vendors,
> works only for ARM)

Unfortunate - I'm getting rather annoyed with the way vendors create
these derivatives of ARM hardware which then cause problems for the
kernel, springing up all these vendor specific hacks all over the
place.

Maybe what we should've done with ZTE is insisted that they implement
a complete new driver, rather than trying to shoe-horn it into PL011
even though it is in theory PL011.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Russell King - ARM Linux]

On Fri, Sep 16, 2016 at 03:23:57PM +0100, Sudeep Holla wrote:
> Hi Shawn, Russell,
> 
> I noticed this change is in linux-next and but I happen to hit an issue
> with this as I tested it with earlycon enabled today for the first time.
> 
> On 08/07/16 10:00, Shawn Guo wrote:
> >For some reason we do not really understand, ZTE hardware designers
> >choose to define PL011 Flag Register bit positions differently from
> >standard ones as below.
> >
> >	Bit		Standard	ZTE
> >	-----------------------------------
> >	CTS		0		1
> >	DSR		1		3
> >	BUSY		3		8
> >	RI		8		0
> >
> >Let's define these bits into vendor data and get ZTE PL011 supported
> >properly.
> >
> >Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> 
> [...]
> 
> >@@ -2303,13 +2325,16 @@ static struct console amba_console = {
> >
> > static void pl011_putc(struct uart_port *port, int c)
> > {
> >+	struct uart_amba_port *uap =
> >+		container_of(port, struct uart_amba_port, port);
> >+
> > 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> > 		cpu_relax();
> > 	if (port->iotype == UPIO_MEM32)
> > 		writel(c, port->membase + UART01x_DR);
> > 	else
> > 		writeb(c, port->membase + UART01x_DR);
> >-	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> >+	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
> > 		cpu_relax();
> > }
> 
> The above hunk won't work for early console devices. The earlycon_device
> just has uart_port and is not uart_amba_port. I don't know how to fix
> this properly but I thought we could reuse private_data in uart_port for
> early_con devices. Something like below(incomplete for other vendors,
> works only for ARM)

Unfortunate - I'm getting rather annoyed with the way vendors create
these derivatives of ARM hardware which then cause problems for the
kernel, springing up all these vendor specific hacks all over the
place.

Maybe what we should've done with ZTE is insisted that they implement
a complete new driver, rather than trying to shoe-horn it into PL011
even though it is in theory PL011.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

Re: [PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Timur Tabi]

Russell King - ARM Linux wrote:
> Maybe what we should've done with ZTE is insisted that they implement
> a complete new driver, rather than trying to shoe-horn it into PL011
> even though it is in theory PL011.

When I suggested that a year ago, I was shot down:

http://www.spinics.net/lists/arm-kernel/msg455888.html

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[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Timur Tabi]

Russell King - ARM Linux wrote:
> Maybe what we should've done with ZTE is insisted that they implement
> a complete new driver, rather than trying to shoe-horn it into PL011
> even though it is in theory PL011.

When I suggested that a year ago, I was shot down:

http://www.spinics.net/lists/arm-kernel/msg455888.html

-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc.  Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

Re: [PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Shawn Guo]

On Fri, Sep 16, 2016 at 03:23:57PM +0100, Sudeep Holla wrote:
> >@@ -2303,13 +2325,16 @@ static struct console amba_console = {
> >
> > static void pl011_putc(struct uart_port *port, int c)
> > {
> >+	struct uart_amba_port *uap =
> >+		container_of(port, struct uart_amba_port, port);
> >+
> > 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> > 		cpu_relax();
> > 	if (port->iotype == UPIO_MEM32)
> > 		writel(c, port->membase + UART01x_DR);
> > 	else
> > 		writeb(c, port->membase + UART01x_DR);
> >-	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> >+	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
> > 		cpu_relax();
> > }
> 
> The above hunk won't work for early console devices. The earlycon_device
> just has uart_port and is not uart_amba_port. I don't know how to fix
> this properly but I thought we could reuse private_data in uart_port for
> early_con devices. Something like below(incomplete for other vendors,
> works only for ARM)

Hi Sudeep,

Thanks much for the report.  I think the best way to fix this is that we
revert the change for pl011_putc() function, and figure out a correct
approach adding earlycon support for ZTE hardware later.

I will send a patch to revert pl011_putc() changes shortly.

Thanks,
Shawn

[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Shawn Guo]

On Fri, Sep 16, 2016 at 03:23:57PM +0100, Sudeep Holla wrote:
> >@@ -2303,13 +2325,16 @@ static struct console amba_console = {
> >
> > static void pl011_putc(struct uart_port *port, int c)
> > {
> >+	struct uart_amba_port *uap =
> >+		container_of(port, struct uart_amba_port, port);
> >+
> > 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> > 		cpu_relax();
> > 	if (port->iotype == UPIO_MEM32)
> > 		writel(c, port->membase + UART01x_DR);
> > 	else
> > 		writeb(c, port->membase + UART01x_DR);
> >-	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> >+	while (readl(port->membase + UART01x_FR) & uap->vendor->fr_busy)
> > 		cpu_relax();
> > }
> 
> The above hunk won't work for early console devices. The earlycon_device
> just has uart_port and is not uart_amba_port. I don't know how to fix
> this properly but I thought we could reuse private_data in uart_port for
> early_con devices. Something like below(incomplete for other vendors,
> works only for ARM)

Hi Sudeep,

Thanks much for the report.  I think the best way to fix this is that we
revert the change for pl011_putc() function, and figure out a correct
approach adding earlycon support for ZTE hardware later.

I will send a patch to revert pl011_putc() changes shortly.

Thanks,
Shawn

Re: [PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Shawn Guo]

On Fri, Sep 16, 2016 at 12:11:05PM -0500, Timur Tabi wrote:
> Russell King - ARM Linux wrote:
> >Maybe what we should've done with ZTE is insisted that they implement
> >a complete new driver, rather than trying to shoe-horn it into PL011
> >even though it is in theory PL011.
> 
> When I suggested that a year ago, I was shot down:
> 
> http://www.spinics.net/lists/arm-kernel/msg455888.html

I still think that's a bad idea.  ZTE is not the first one making such
small customization on PL011, and likely won't be the last one.  We
don't want to clone PL011 driver every time there is a such vendor
hardware coming out, do we?  Having PL011 driver being able to handle
different register layout is very helpful to handle such vendor
variants, IMHO.

I still appreciate rmk's insistence to handle ZTE device with PL011
driver, and the effort of adding a little "infrastructure" to handle
all such possible variants.

Shawn

[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Shawn Guo]

On Fri, Sep 16, 2016 at 12:11:05PM -0500, Timur Tabi wrote:
> Russell King - ARM Linux wrote:
> >Maybe what we should've done with ZTE is insisted that they implement
> >a complete new driver, rather than trying to shoe-horn it into PL011
> >even though it is in theory PL011.
> 
> When I suggested that a year ago, I was shot down:
> 
> http://www.spinics.net/lists/arm-kernel/msg455888.html

I still think that's a bad idea.  ZTE is not the first one making such
small customization on PL011, and likely won't be the last one.  We
don't want to clone PL011 driver every time there is a such vendor
hardware coming out, do we?  Having PL011 driver being able to handle
different register layout is very helpful to handle such vendor
variants, IMHO.

I still appreciate rmk's insistence to handle ZTE device with PL011
driver, and the effort of adding a little "infrastructure" to handle
all such possible variants.

Shawn

Re: [PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Russell King - ARM Linux]

On Sat, Sep 17, 2016 at 01:37:53PM +0800, Shawn Guo wrote:
> I still think that's a bad idea.  ZTE is not the first one making such
> small customization on PL011, and likely won't be the last one.  We
> don't want to clone PL011 driver every time there is a such vendor
> hardware coming out, do we?  Having PL011 driver being able to handle
> different register layout is very helpful to handle such vendor
> variants, IMHO.

Well, it's turning out that handling ZTE in PL011 is turning into a
bad idea as well - we keep getting these breakages each time we try.

I think ZTE is sufficiently different from PL011 with the different
register layout _and_ the different bits, _and_ the pain that this
is causing, that it should have been a separate driver.

The only way I can think of dealing with the console issue is to
replicate the console code, once for the PL011 variant and then
again for the ZTE variant.  We can't _both_ give them the same names
_and_ register them together - we either have to give them different
names, which makes it confusing because one name won't match the
userspace name for the UART, or we need the driver to detect the
port type early.  That's made much more difficult because ZTE didn't
bother with the ID registers, unlike every other vendor.

Serial drivers are not that complex anymore, compared to how they
were back before serial_core happened, so having it as a separate
driver isn't that big a deal.

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[PATCH v3 1/3] tty: amba-pl011: define flag register bits for ZTE device

[Russell King - ARM Linux]

On Sat, Sep 17, 2016 at 01:37:53PM +0800, Shawn Guo wrote:
> I still think that's a bad idea.  ZTE is not the first one making such
> small customization on PL011, and likely won't be the last one.  We
> don't want to clone PL011 driver every time there is a such vendor
> hardware coming out, do we?  Having PL011 driver being able to handle
> different register layout is very helpful to handle such vendor
> variants, IMHO.

Well, it's turning out that handling ZTE in PL011 is turning into a
bad idea as well - we keep getting these breakages each time we try.

I think ZTE is sufficiently different from PL011 with the different
register layout _and_ the different bits, _and_ the pain that this
is causing, that it should have been a separate driver.

The only way I can think of dealing with the console issue is to
replicate the console code, once for the PL011 variant and then
again for the ZTE variant.  We can't _both_ give them the same names
_and_ register them together - we either have to give them different
names, which makes it confusing because one name won't match the
userspace name for the UART, or we need the driver to detect the
port type early.  That's made much more difficult because ZTE didn't
bother with the ID registers, unlike every other vendor.

Serial drivers are not that complex anymore, compared to how they
were back before serial_core happened, so having it as a separate
driver isn't that big a deal.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.