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Subject[PATCH 08/12] [Blackfin] serial driver: fix bug - cache the bits of the LSR on systems where the LSR is read-to-clear
Date
From: Mike Frysinger <michael.frysinger@analog.com>

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>
---
drivers/serial/bfin_5xx.c | 10 +++++++---
include/asm-blackfin/mach-bf527/bfin_serial_5xx.h | 19 ++++++++++++++++++-
include/asm-blackfin/mach-bf533/bfin_serial_5xx.h | 19 ++++++++++++++++++-
include/asm-blackfin/mach-bf537/bfin_serial_5xx.h | 19 ++++++++++++++++++-
include/asm-blackfin/mach-bf548/bfin_serial_5xx.h | 1 +
include/asm-blackfin/mach-bf561/bfin_serial_5xx.h | 19 ++++++++++++++++++-
6 files changed, 80 insertions(+), 7 deletions(-)

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index ca9ceaa..af84984 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -216,8 +216,10 @@ static void bfin_serial_rx_chars(struct bfin_serial_port *uart)
struct pt_regs *regs = get_irq_regs();
#endif

- ch = UART_GET_CHAR(uart);
status = UART_GET_LSR(uart);
+ UART_CLEAR_LSR(uart);
+
+ ch = UART_GET_CHAR(uart);
uart->port.icount.rx++;

#ifdef CONFIG_KGDB_UART
@@ -335,7 +337,7 @@ static irqreturn_t bfin_serial_rx_int(int irq, void *dev_id)
struct bfin_serial_port *uart = dev_id;

spin_lock(&uart->port.lock);
- while ((UART_GET_IER(uart) & ERBFI) && (UART_GET_LSR(uart) & DR))
+ while (UART_GET_LSR(uart) & DR)
bfin_serial_rx_chars(uart);
spin_unlock(&uart->port.lock);

@@ -347,7 +349,7 @@ static irqreturn_t bfin_serial_tx_int(int irq, void *dev_id)
struct bfin_serial_port *uart = dev_id;

spin_lock(&uart->port.lock);
- if ((UART_GET_IER(uart) & ETBEI) && (UART_GET_LSR(uart) & THRE))
+ if (UART_GET_LSR(uart) & THRE)
bfin_serial_tx_chars(uart);
spin_unlock(&uart->port.lock);

@@ -428,6 +430,8 @@ static void bfin_serial_dma_rx_chars(struct bfin_serial_port *uart)
int i, flg, status;

status = UART_GET_LSR(uart);
+ UART_CLEAR_LSR(uart);
+
uart->port.icount.rx += CIRC_CNT(uart->rx_dma_buf.head, uart->rx_dma_buf.tail, UART_XMIT_SIZE);;

if (status & BI) {
diff --git a/include/asm-blackfin/mach-bf527/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf527/bfin_serial_5xx.h
index 15dbc21..233c585 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 7871d43..b619065 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 86e45c3..f18c517 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 3770aa3..8733d47 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 7871d43..b619065 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;
--
1.5.3.4

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