/*
- * linux/drivers/char/amba.c
- *
* Driver for AMBA serial ports
*
* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
#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>
#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;
unsigned int lcrh_tx;
unsigned int lcrh_rx;
bool oversampling;
+ bool interrupt_may_hang; /* vendor-specific */
bool dma_threshold;
};
.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 {
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;
#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;
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);
unsigned int cr;
int retval;
+ retval = clk_prepare(uap->clk);
+ if (retval)
+ goto out;
+
/*
* Try to enable the clock producer.
*/
retval = clk_enable(uap->clk);
if (retval)
- goto out;
+ goto clk_unprep;
uap->port.uartclk = clk_get_rate(uap->clk);
+ /* Clear pending error and receive interrupts */
+ writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS |
+ UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
+
/*
* Allocate the IRQ
*/
cr = UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;
writew(cr, uap->port.membase + UART011_CR);
- /* Clear pending error interrupts */
- writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS,
- uap->port.membase + UART011_ICR);
-
/*
* initialise the old status of the modem signals
*/
* as well.
*/
spin_lock_irq(&uap->port.lock);
+ /* Clear out any spuriously appearing RX interrupts */
+ writew(UART011_RTIS | UART011_RXIS,
+ uap->port.membase + UART011_ICR);
uap->im = UART011_RTIM;
if (!pl011_dma_rx_running(uap))
uap->im |= UART011_RXIM;
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:
clk_disable(uap->clk);
+ clk_unprep:
+ clk_unprepare(uap->clk);
out:
return retval;
}
* Shut down the clock producer
*/
clk_disable(uap->clk);
+ clk_unprepare(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
{
struct uart_amba_port *uap = amba_ports[co->index];
unsigned int status, old_cr, new_cr;
+ unsigned long flags;
+ int locked = 1;
clk_enable(uap->clk);
+ local_irq_save(flags);
+ if (uap->port.sysrq)
+ locked = 0;
+ else if (oops_in_progress)
+ locked = spin_trylock(&uap->port.lock);
+ else
+ spin_lock(&uap->port.lock);
+
/*
* First save the CR then disable the interrupts
*/
} while (status & UART01x_FR_BUSY);
writew(old_cr, uap->port.membase + UART011_CR);
+ if (locked)
+ spin_unlock(&uap->port.lock);
+ local_irq_restore(flags);
+
clk_disable(uap->clk);
}
int bits = 8;
int parity = 'n';
int flow = 'n';
+ int ret;
/*
* Check whether an invalid uart number has been specified, and
if (!uap)
return -ENODEV;
+ ret = clk_prepare(uap->clk);
+ if (ret)
+ return ret;
+
+ 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)
goto unmap;
}
+ /* Ensure interrupts from this UART are masked and cleared */
+ writew(0, uap->port.membase + UART011_IMSC);
+ writew(0xffff, uap->port.membase + UART011_ICR);
+
uap->vendor = vendor;
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;
projects / linux-flexiantxendom0.git / blobdiff