1 files changed, 122 insertions, 1 deletions

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8dc0541feecc..f5f6831b0a64 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -50,6 +50,7 @@
 #include <linux/dmaengine.h>
 #include <linux/dma-mapping.h>
 #include <linux/scatterlist.h>
+#include <linux/delay.h>
 
 #include <asm/io.h>
 #include <asm/sizes.h>
@@ -65,6 +66,30 @@
 #define UART_DR_ERROR           (UART011_DR_OE|UART011_DR_BE|UART011_DR_PE|UART011_DR_FE)
 #define UART_DUMMY_DR_RX        (1 << 16)
 
+
+#define UART_WA_SAVE_NR 14
+
+static void pl011_lockup_wa(unsigned long data);
+static const u32 uart_wa_reg[UART_WA_SAVE_NR] = {
+        ST_UART011_DMAWM,
+        ST_UART011_TIMEOUT,
+        ST_UART011_LCRH_RX,
+        UART011_IBRD,
+        UART011_FBRD,
+        ST_UART011_LCRH_TX,
+        UART011_IFLS,
+        ST_UART011_XFCR,
+        ST_UART011_XON1,
+        ST_UART011_XON2,
+        ST_UART011_XOFF1,
+        ST_UART011_XOFF2,
+        UART011_CR,
+        UART011_IMSC
+};
+
+static u32 uart_wa_regdata[UART_WA_SAVE_NR];
+static DECLARE_TASKLET(pl011_lockup_tlet, pl011_lockup_wa, 0);
+
 /* There is by now at least one vendor with differing details, so handle it */
 struct vendor_data {
         unsigned int            ifls;
@@ -72,6 +97,7 @@ struct vendor_data {
         unsigned int            lcrh_tx;
         unsigned int            lcrh_rx;
         bool                    oversampling;
+        bool                    interrupt_may_hang;   /* vendor-specific */
         bool                    dma_threshold;
 };
 
@@ -90,9 +116,12 @@ static struct vendor_data vendor_st = {
         .lcrh_tx                = ST_UART011_LCRH_TX,
         .lcrh_rx                = ST_UART011_LCRH_RX,
         .oversampling           = true,
+        .interrupt_may_hang     = true,
         .dma_threshold          = true,
 };
 
+static struct uart_amba_port *amba_ports[UART_NR];
+
 /* Deals with DMA transactions */
 
 struct pl011_sgbuf {
@@ -132,6 +161,7 @@ struct uart_amba_port {
         unsigned int            lcrh_rx;        /* vendor-specific */
         bool                    autorts;
         char                    type[12];
+        bool                    interrupt_may_hang; /* vendor-specific */
 #ifdef CONFIG_DMA_ENGINE
         /* DMA stuff */
         bool                    using_tx_dma;
@@ -1008,6 +1038,68 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
 #endif
 
 
+/*
+ * pl011_lockup_wa
+ * This workaround aims to break the deadlock situation
+ * when after long transfer over uart in hardware flow
+ * control, uart interrupt registers cannot be cleared.
+ * Hence uart transfer gets blocked.
+ *
+ * It is seen that during such deadlock condition ICR
+ * don't get cleared even on multiple write. This leads
+ * pass_counter to decrease and finally reach zero. This
+ * can be taken as trigger point to run this UART_BT_WA.
+ *
+ */
+static void pl011_lockup_wa(unsigned long data)
+{
+        struct uart_amba_port *uap = amba_ports[0];
+        void __iomem *base = uap->port.membase;
+        struct circ_buf *xmit = &uap->port.state->xmit;
+        struct tty_struct *tty = uap->port.state->port.tty;
+        int buf_empty_retries = 200;
+        int loop;
+
+        /* Stop HCI layer from submitting data for tx */
+        tty->hw_stopped = 1;
+        while (!uart_circ_empty(xmit)) {
+                if (buf_empty_retries-- == 0)
+                        break;
+                udelay(100);
+        }
+
+        /* Backup registers */
+        for (loop = 0; loop < UART_WA_SAVE_NR; loop++)
+                uart_wa_regdata[loop] = readl(base + uart_wa_reg[loop]);
+
+        /* Disable UART so that FIFO data is flushed out */
+        writew(0x00, uap->port.membase + UART011_CR);
+
+        /* Soft reset UART module */
+        if (uap->port.dev->platform_data) {
+                struct amba_pl011_data *plat;
+
+                plat = uap->port.dev->platform_data;
+                if (plat->reset)
+                        plat->reset();
+        }
+
+        /* Restore registers */
+        for (loop = 0; loop < UART_WA_SAVE_NR; loop++)
+                writew(uart_wa_regdata[loop] ,
+                                uap->port.membase + uart_wa_reg[loop]);
+
+        /* Initialise the old status of the modem signals */
+        uap->old_status = readw(uap->port.membase + UART01x_FR) &
+                UART01x_FR_MODEM_ANY;
+
+        if (readl(base + UART011_MIS) & 0x2)
+                printk(KERN_EMERG "UART_BT_WA: ***FAILED***\n");
+
+        /* Start Tx/Rx */
+        tty->hw_stopped = 0;
+}
+
 static void pl011_stop_tx(struct uart_port *port)
 {
         struct uart_amba_port *uap = (struct uart_amba_port *)port;
@@ -1158,8 +1250,11 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
                         if (status & UART011_TXIS)
                                 pl011_tx_chars(uap);
 
-                        if (pass_counter-- == 0)
+                        if (pass_counter-- == 0) {
+                                if (uap->interrupt_may_hang)
+                                        tasklet_schedule(&pl011_lockup_tlet);
                                 break;
+                        }
 
                         status = readw(uap->port.membase + UART011_MIS);
                 } while (status != 0);
@@ -1339,6 +1434,14 @@ static int pl011_startup(struct uart_port *port)
         writew(uap->im, uap->port.membase + UART011_IMSC);
         spin_unlock_irq(&uap->port.lock);
 
+        if (uap->port.dev->platform_data) {
+                struct amba_pl011_data *plat;
+
+                plat = uap->port.dev->platform_data;
+                if (plat->init)
+                        plat->init();
+        }
+
         return 0;
 
  clk_dis:
@@ -1394,6 +1497,15 @@ static void pl011_shutdown(struct uart_port *port)
          * Shut down the clock producer
          */
         clk_disable(uap->clk);
+
+        if (uap->port.dev->platform_data) {
+                struct amba_pl011_data *plat;
+
+                plat = uap->port.dev->platform_data;
+                if (plat->exit)
+                        plat->exit();
+        }
+
 }
 
 static void
@@ -1700,6 +1812,14 @@ static int __init pl011_console_setup(struct console *co, char *options)
         if (!uap)
                 return -ENODEV;
 
+        if (uap->port.dev->platform_data) {
+                struct amba_pl011_data *plat;
+
+                plat = uap->port.dev->platform_data;
+                if (plat->init)
+                        plat->init();
+        }
+
         uap->port.uartclk = clk_get_rate(uap->clk);
 
         if (options)
@@ -1774,6 +1894,7 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
         uap->lcrh_rx = vendor->lcrh_rx;
         uap->lcrh_tx = vendor->lcrh_tx;
         uap->fifosize = vendor->fifosize;
+        uap->interrupt_may_hang = vendor->interrupt_may_hang;
         uap->port.dev = &dev->dev;
         uap->port.mapbase = dev->res.start;
         uap->port.membase = base;