[Blackfin] serial driver: fix bug - cache the bits of the LSR on systems where the LSR is read-to-clear

Cache the bits of the LSR on systems where the LSR is read-to-clear
so that we can safely read the LSR in random places.  this fixes
older parts where break/framing/parity/overflow was not being detected
at all in PIO mode, and this fixes newer parts where
break/framing/parity/overflow was being reported all the time
without being cleared.

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

5 files changed, 73 insertions, 4 deletions

diff --git a/include/asm-blackfin/mach-bf527/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf527/bfin_serial_5xx.h
index 15dbc21eed8b..233c585efc1e 100644
--- a/include/asm-blackfin/mach-bf527/bfin_serial_5xx.h
+++ b/include/asm-blackfin/mach-bf527/bfin_serial_5xx.h
@@ -23,7 +23,6 @@
 #define UART_GET_DLH(uart)      bfin_read16(((uart)->port.membase + OFFSET_DLH))
 #define UART_GET_IIR(uart)      bfin_read16(((uart)->port.membase + OFFSET_IIR))
 #define UART_GET_LCR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LCR))
-#define UART_GET_LSR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LSR))
 #define UART_GET_GCTL(uart)     bfin_read16(((uart)->port.membase + OFFSET_GCTL))
 
 #define UART_PUT_CHAR(uart, v)   bfin_write16(((uart)->port.membase + OFFSET_THR), v)
@@ -58,6 +57,7 @@
 struct bfin_serial_port {
         struct uart_port port;
         unsigned int old_status;
+        unsigned int lsr;
 #ifdef CONFIG_SERIAL_BFIN_DMA
         int tx_done;
         int tx_count;
@@ -76,6 +76,23 @@ struct bfin_serial_port {
 #endif
 };
 
+/* The hardware clears the LSR bits upon read, so we need to cache
+ * some of the more fun bits in software so they don't get lost
+ * when checking the LSR in other code paths (TX).
+ */
+static inline unsigned int UART_GET_LSR(struct bfin_serial_port *uart)
+{
+        unsigned int lsr = bfin_read16(uart->port.membase + OFFSET_LSR);
+        uart->lsr |= (lsr & (BI|FE|PE|OE));
+        return lsr | uart->lsr;
+}
+
+static inline void UART_CLEAR_LSR(struct bfin_serial_port *uart)
+{
+        uart->lsr = 0;
+        bfin_write16(uart->port.membase + OFFSET_LSR, -1);
+}
+
 struct bfin_serial_port bfin_serial_ports[NR_PORTS];
 struct bfin_serial_res {
         unsigned long uart_base_addr;
diff --git a/include/asm-blackfin/mach-bf533/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf533/bfin_serial_5xx.h
index 7871d4313f49..b619065ceeb0 100644
--- a/include/asm-blackfin/mach-bf533/bfin_serial_5xx.h
+++ b/include/asm-blackfin/mach-bf533/bfin_serial_5xx.h
@@ -23,7 +23,6 @@
 #define UART_GET_DLH(uart)      bfin_read16(((uart)->port.membase + OFFSET_DLH))
 #define UART_GET_IIR(uart)      bfin_read16(((uart)->port.membase + OFFSET_IIR))
 #define UART_GET_LCR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LCR))
-#define UART_GET_LSR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LSR))
 #define UART_GET_GCTL(uart)     bfin_read16(((uart)->port.membase + OFFSET_GCTL))
 
 #define UART_PUT_CHAR(uart,v)   bfin_write16(((uart)->port.membase + OFFSET_THR),v)
@@ -46,6 +45,7 @@
 struct bfin_serial_port {
         struct uart_port        port;
         unsigned int            old_status;
+        unsigned int lsr;
 #ifdef CONFIG_SERIAL_BFIN_DMA
         int                     tx_done;
         int                     tx_count;
@@ -64,6 +64,23 @@ struct bfin_serial_port {
 #endif
 };
 
+/* The hardware clears the LSR bits upon read, so we need to cache
+ * some of the more fun bits in software so they don't get lost
+ * when checking the LSR in other code paths (TX).
+ */
+static inline unsigned int UART_GET_LSR(struct bfin_serial_port *uart)
+{
+        unsigned int lsr = bfin_read16(uart->port.membase + OFFSET_LSR);
+        uart->lsr |= (lsr & (BI|FE|PE|OE));
+        return lsr | uart->lsr;
+}
+
+static inline void UART_CLEAR_LSR(struct bfin_serial_port *uart)
+{
+        uart->lsr = 0;
+        bfin_write16(uart->port.membase + OFFSET_LSR, -1);
+}
+
 struct bfin_serial_port bfin_serial_ports[NR_PORTS];
 struct bfin_serial_res {
         unsigned long   uart_base_addr;
diff --git a/include/asm-blackfin/mach-bf537/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf537/bfin_serial_5xx.h
index 86e45c379838..f18c517cc935 100644
--- a/include/asm-blackfin/mach-bf537/bfin_serial_5xx.h
+++ b/include/asm-blackfin/mach-bf537/bfin_serial_5xx.h
@@ -23,7 +23,6 @@
 #define UART_GET_DLH(uart)      bfin_read16(((uart)->port.membase + OFFSET_DLH))
 #define UART_GET_IIR(uart)      bfin_read16(((uart)->port.membase + OFFSET_IIR))
 #define UART_GET_LCR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LCR))
-#define UART_GET_LSR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LSR))
 #define UART_GET_GCTL(uart)     bfin_read16(((uart)->port.membase + OFFSET_GCTL))
 
 #define UART_PUT_CHAR(uart,v)   bfin_write16(((uart)->port.membase + OFFSET_THR),v)
@@ -58,6 +57,7 @@
 struct bfin_serial_port {
         struct uart_port        port;
         unsigned int            old_status;
+        unsigned int lsr;
 #ifdef CONFIG_SERIAL_BFIN_DMA
         int                     tx_done;
         int                     tx_count;
@@ -76,6 +76,23 @@ struct bfin_serial_port {
 #endif
 };
 
+/* The hardware clears the LSR bits upon read, so we need to cache
+ * some of the more fun bits in software so they don't get lost
+ * when checking the LSR in other code paths (TX).
+ */
+static inline unsigned int UART_GET_LSR(struct bfin_serial_port *uart)
+{
+        unsigned int lsr = bfin_read16(uart->port.membase + OFFSET_LSR);
+        uart->lsr |= (lsr & (BI|FE|PE|OE));
+        return lsr | uart->lsr;
+}
+
+static inline void UART_CLEAR_LSR(struct bfin_serial_port *uart)
+{
+        uart->lsr = 0;
+        bfin_write16(uart->port.membase + OFFSET_LSR, -1);
+}
+
 struct bfin_serial_port bfin_serial_ports[NR_PORTS];
 struct bfin_serial_res {
         unsigned long   uart_base_addr;
diff --git a/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h
index 3770aa38ee9f..8733d47747e5 100644
--- a/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h
+++ b/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h
@@ -32,6 +32,7 @@
 #define UART_PUT_DLH(uart,v)    bfin_write16(((uart)->port.membase + OFFSET_DLH),v)
 #define UART_PUT_LSR(uart,v)    bfin_write16(((uart)->port.membase + OFFSET_LSR),v)
 #define UART_PUT_LCR(uart,v)    bfin_write16(((uart)->port.membase + OFFSET_LCR),v)
+#define UART_CLEAR_LSR(uart)    bfin_write16(((uart)->port.membase + OFFSET_LSR), -1)
 #define UART_PUT_GCTL(uart,v)   bfin_write16(((uart)->port.membase + OFFSET_GCTL),v)
 
 #if defined(CONFIG_BFIN_UART0_CTSRTS) || defined(CONFIG_BFIN_UART1_CTSRTS)
diff --git a/include/asm-blackfin/mach-bf561/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf561/bfin_serial_5xx.h
index 7871d4313f49..b619065ceeb0 100644
--- a/include/asm-blackfin/mach-bf561/bfin_serial_5xx.h
+++ b/include/asm-blackfin/mach-bf561/bfin_serial_5xx.h
@@ -23,7 +23,6 @@
 #define UART_GET_DLH(uart)      bfin_read16(((uart)->port.membase + OFFSET_DLH))
 #define UART_GET_IIR(uart)      bfin_read16(((uart)->port.membase + OFFSET_IIR))
 #define UART_GET_LCR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LCR))
-#define UART_GET_LSR(uart)      bfin_read16(((uart)->port.membase + OFFSET_LSR))
 #define UART_GET_GCTL(uart)     bfin_read16(((uart)->port.membase + OFFSET_GCTL))
 
 #define UART_PUT_CHAR(uart,v)   bfin_write16(((uart)->port.membase + OFFSET_THR),v)
@@ -46,6 +45,7 @@
 struct bfin_serial_port {
         struct uart_port        port;
         unsigned int            old_status;
+        unsigned int lsr;
 #ifdef CONFIG_SERIAL_BFIN_DMA
         int                     tx_done;
         int                     tx_count;
@@ -64,6 +64,23 @@ struct bfin_serial_port {
 #endif
 };
 
+/* The hardware clears the LSR bits upon read, so we need to cache
+ * some of the more fun bits in software so they don't get lost
+ * when checking the LSR in other code paths (TX).
+ */
+static inline unsigned int UART_GET_LSR(struct bfin_serial_port *uart)
+{
+        unsigned int lsr = bfin_read16(uart->port.membase + OFFSET_LSR);
+        uart->lsr |= (lsr & (BI|FE|PE|OE));
+        return lsr | uart->lsr;
+}
+
+static inline void UART_CLEAR_LSR(struct bfin_serial_port *uart)
+{
+        uart->lsr = 0;
+        bfin_write16(uart->port.membase + OFFSET_LSR, -1);
+}
+
 struct bfin_serial_port bfin_serial_ports[NR_PORTS];
 struct bfin_serial_res {
         unsigned long   uart_base_addr;