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path: root/drivers/tty/serial/amba-pl011.c
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Diffstat (limited to 'drivers/tty/serial/amba-pl011.c')
-rw-r--r--drivers/tty/serial/amba-pl011.c177
1 files changed, 133 insertions, 44 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d3553b5d3fca..d7e1edec50b5 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -52,6 +52,8 @@
#include <linux/scatterlist.h>
#include <linux/delay.h>
#include <linux/types.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/sizes.h>
@@ -75,7 +77,6 @@ struct vendor_data {
unsigned int lcrh_tx;
unsigned int lcrh_rx;
bool oversampling;
- bool interrupt_may_hang; /* vendor-specific */
bool dma_threshold;
bool cts_event_workaround;
};
@@ -96,7 +97,6 @@ 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,
.cts_event_workaround = true,
};
@@ -147,7 +147,6 @@ struct uart_amba_port {
unsigned int old_cr; /* state during shutdown */
bool autorts;
char type[12];
- bool interrupt_may_hang; /* vendor-specific */
#ifdef CONFIG_DMA_ENGINE
/* DMA stuff */
bool using_tx_dma;
@@ -1215,14 +1214,14 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
return IRQ_RETVAL(handled);
}
-static unsigned int pl01x_tx_empty(struct uart_port *port)
+static unsigned int pl011_tx_empty(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status = readw(uap->port.membase + UART01x_FR);
return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
}
-static unsigned int pl01x_get_mctrl(struct uart_port *port)
+static unsigned int pl011_get_mctrl(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int result = 0;
@@ -1285,11 +1284,40 @@ static void pl011_break_ctl(struct uart_port *port, int break_state)
}
#ifdef CONFIG_CONSOLE_POLL
-static int pl010_get_poll_char(struct uart_port *port)
+
+static void pl011_quiesce_irqs(struct uart_port *port)
+{
+ struct uart_amba_port *uap = (struct uart_amba_port *)port;
+ unsigned char __iomem *regs = uap->port.membase;
+
+ writew(readw(regs + UART011_MIS), regs + UART011_ICR);
+ /*
+ * There is no way to clear TXIM as this is "ready to transmit IRQ", so
+ * we simply mask it. start_tx() will unmask it.
+ *
+ * Note we can race with start_tx(), and if the race happens, the
+ * polling user might get another interrupt just after we clear it.
+ * But it should be OK and can happen even w/o the race, e.g.
+ * controller immediately got some new data and raised the IRQ.
+ *
+ * And whoever uses polling routines assumes that it manages the device
+ * (including tx queue), so we're also fine with start_tx()'s caller
+ * side.
+ */
+ writew(readw(regs + UART011_IMSC) & ~UART011_TXIM, regs + UART011_IMSC);
+}
+
+static int pl011_get_poll_char(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status;
+ /*
+ * The caller might need IRQs lowered, e.g. if used with KDB NMI
+ * debugger.
+ */
+ pl011_quiesce_irqs(port);
+
status = readw(uap->port.membase + UART01x_FR);
if (status & UART01x_FR_RXFE)
return NO_POLL_CHAR;
@@ -1297,7 +1325,7 @@ static int pl010_get_poll_char(struct uart_port *port)
return readw(uap->port.membase + UART01x_DR);
}
-static void pl010_put_poll_char(struct uart_port *port,
+static void pl011_put_poll_char(struct uart_port *port,
unsigned char ch)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
@@ -1310,10 +1338,9 @@ static void pl010_put_poll_char(struct uart_port *port,
#endif /* CONFIG_CONSOLE_POLL */
-static int pl011_startup(struct uart_port *port)
+static int pl011_hwinit(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
- unsigned int cr;
int retval;
/* Optionaly enable pins to be muxed in and configured */
@@ -1324,16 +1351,12 @@ static int pl011_startup(struct uart_port *port)
"could not set default pins\n");
}
- retval = clk_prepare(uap->clk);
- if (retval)
- goto out;
-
/*
* Try to enable the clock producer.
*/
- retval = clk_enable(uap->clk);
+ retval = clk_prepare_enable(uap->clk);
if (retval)
- goto clk_unprep;
+ goto out;
uap->port.uartclk = clk_get_rate(uap->clk);
@@ -1342,6 +1365,37 @@ static int pl011_startup(struct uart_port *port)
UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
/*
+ * Save interrupts enable mask, and enable RX interrupts in case if
+ * the interrupt is used for NMI entry.
+ */
+ uap->im = readw(uap->port.membase + UART011_IMSC);
+ writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
+
+ if (uap->port.dev->platform_data) {
+ struct amba_pl011_data *plat;
+
+ plat = uap->port.dev->platform_data;
+ if (plat->init)
+ plat->init();
+ }
+ return 0;
+ out:
+ return retval;
+}
+
+static int pl011_startup(struct uart_port *port)
+{
+ struct uart_amba_port *uap = (struct uart_amba_port *)port;
+ unsigned int cr;
+ int retval;
+
+ retval = pl011_hwinit(port);
+ if (retval)
+ goto clk_dis;
+
+ writew(uap->im, uap->port.membase + UART011_IMSC);
+
+ /*
* Allocate the IRQ
*/
retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
@@ -1400,21 +1454,10 @@ 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:
- clk_disable(uap->clk);
- clk_unprep:
- clk_unprepare(uap->clk);
- out:
+ clk_disable_unprepare(uap->clk);
return retval;
}
@@ -1473,8 +1516,7 @@ static void pl011_shutdown(struct uart_port *port)
/*
* Shut down the clock producer
*/
- clk_disable(uap->clk);
- clk_unprepare(uap->clk);
+ clk_disable_unprepare(uap->clk);
/* Optionally let pins go into sleep states */
if (!IS_ERR(uap->pins_sleep)) {
retval = pinctrl_select_state(uap->pinctrl, uap->pins_sleep);
@@ -1603,13 +1645,26 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
old_cr &= ~ST_UART011_CR_OVSFACT;
}
+ /*
+ * Workaround for the ST Micro oversampling variants to
+ * increase the bitrate slightly, by lowering the divisor,
+ * to avoid delayed sampling of start bit at high speeds,
+ * else we see data corruption.
+ */
+ if (uap->vendor->oversampling) {
+ if ((baud >= 3000000) && (baud < 3250000) && (quot > 1))
+ quot -= 1;
+ else if ((baud > 3250000) && (quot > 2))
+ quot -= 2;
+ }
/* Set baud rate */
writew(quot & 0x3f, port->membase + UART011_FBRD);
writew(quot >> 6, port->membase + UART011_IBRD);
/*
* ----------v----------v----------v----------v-----
- * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
+ * NOTE: lcrh_tx and lcrh_rx MUST BE WRITTEN AFTER
+ * UART011_FBRD & UART011_IBRD.
* ----------^----------^----------^----------^-----
*/
writew(lcr_h, port->membase + uap->lcrh_rx);
@@ -1637,7 +1692,7 @@ static const char *pl011_type(struct uart_port *port)
/*
* Release the memory region(s) being used by 'port'
*/
-static void pl010_release_port(struct uart_port *port)
+static void pl011_release_port(struct uart_port *port)
{
release_mem_region(port->mapbase, SZ_4K);
}
@@ -1645,7 +1700,7 @@ static void pl010_release_port(struct uart_port *port)
/*
* Request the memory region(s) being used by 'port'
*/
-static int pl010_request_port(struct uart_port *port)
+static int pl011_request_port(struct uart_port *port)
{
return request_mem_region(port->mapbase, SZ_4K, "uart-pl011")
!= NULL ? 0 : -EBUSY;
@@ -1654,18 +1709,18 @@ static int pl010_request_port(struct uart_port *port)
/*
* Configure/autoconfigure the port.
*/
-static void pl010_config_port(struct uart_port *port, int flags)
+static void pl011_config_port(struct uart_port *port, int flags)
{
if (flags & UART_CONFIG_TYPE) {
port->type = PORT_AMBA;
- pl010_request_port(port);
+ pl011_request_port(port);
}
}
/*
* verify the new serial_struct (for TIOCSSERIAL).
*/
-static int pl010_verify_port(struct uart_port *port, struct serial_struct *ser)
+static int pl011_verify_port(struct uart_port *port, struct serial_struct *ser)
{
int ret = 0;
if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMBA)
@@ -1678,9 +1733,9 @@ static int pl010_verify_port(struct uart_port *port, struct serial_struct *ser)
}
static struct uart_ops amba_pl011_pops = {
- .tx_empty = pl01x_tx_empty,
+ .tx_empty = pl011_tx_empty,
.set_mctrl = pl011_set_mctrl,
- .get_mctrl = pl01x_get_mctrl,
+ .get_mctrl = pl011_get_mctrl,
.stop_tx = pl011_stop_tx,
.start_tx = pl011_start_tx,
.stop_rx = pl011_stop_rx,
@@ -1691,13 +1746,14 @@ static struct uart_ops amba_pl011_pops = {
.flush_buffer = pl011_dma_flush_buffer,
.set_termios = pl011_set_termios,
.type = pl011_type,
- .release_port = pl010_release_port,
- .request_port = pl010_request_port,
- .config_port = pl010_config_port,
- .verify_port = pl010_verify_port,
+ .release_port = pl011_release_port,
+ .request_port = pl011_request_port,
+ .config_port = pl011_config_port,
+ .verify_port = pl011_verify_port,
#ifdef CONFIG_CONSOLE_POLL
- .poll_get_char = pl010_get_poll_char,
- .poll_put_char = pl010_put_poll_char,
+ .poll_init = pl011_hwinit,
+ .poll_get_char = pl011_get_poll_char,
+ .poll_put_char = pl011_put_poll_char,
#endif
};
@@ -1869,6 +1925,38 @@ static struct uart_driver amba_reg = {
.cons = AMBA_CONSOLE,
};
+static int pl011_probe_dt_alias(int index, struct device *dev)
+{
+ struct device_node *np;
+ static bool seen_dev_with_alias = false;
+ static bool seen_dev_without_alias = false;
+ int ret = index;
+
+ if (!IS_ENABLED(CONFIG_OF))
+ return ret;
+
+ np = dev->of_node;
+ if (!np)
+ return ret;
+
+ ret = of_alias_get_id(np, "serial");
+ if (IS_ERR_VALUE(ret)) {
+ seen_dev_without_alias = true;
+ ret = index;
+ } else {
+ seen_dev_with_alias = true;
+ if (ret >= ARRAY_SIZE(amba_ports) || amba_ports[ret] != NULL) {
+ dev_warn(dev, "requested serial port %d not available.\n", ret);
+ ret = index;
+ }
+ }
+
+ if (seen_dev_with_alias && seen_dev_without_alias)
+ dev_warn(dev, "aliased and non-aliased serial devices found in device tree. Serial port enumeration may be unpredictable.\n");
+
+ return ret;
+}
+
static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
{
struct uart_amba_port *uap;
@@ -1891,6 +1979,8 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
goto out;
}
+ i = pl011_probe_dt_alias(i, &dev->dev);
+
base = ioremap(dev->res.start, resource_size(&dev->res));
if (!base) {
ret = -ENOMEM;
@@ -1923,7 +2013,6 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
uap->lcrh_tx = vendor->lcrh_tx;
uap->old_cr = 0;
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;