This device does not support changing baud, parity, data bits, stop
bits, or detecting breaks. Disable "changing" these settings to prevent
their termios from diverging from the actual state of the uart. To inform
users of these limitations, warn if the new termios change these
parameters. We only do this once to avoid spamming the log. These
warnings are inspired by those in the sifive driver.
In order to determine the correct parameters to enforce, we read the
various new devicetree parameters to discover how the uart was
configured when it was synthesized. The defaults match
ulite_console_setup. xlnx,use-parity, xlnx,odd-parity, and
xlnx,data-bits are optional since there were in-tree users (and
presumably out-of-tree users) who did not set them.
Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx>
---
Changes in v2:
- Compare the baud computed with uart_get_baud_rate to pdata->baud,
instead of just checking c_cflag. This will catch anything that messes
with ispeed and ospeed.
- Don't bother trying to set the initial termios. Instead, just skip
warning if old is NULL.
- Because we no longer use uart_set_options, just convert the devicetree
properties directly to clflags.
- Merge with [PATCH 4/5] ("tty: serial: uartlite: Initialize termios
with fixed synthesis parameters") to make it clearer what the
properties we read are being used for.
drivers/tty/serial/uartlite.c | 120 ++++++++++++++++++++++++++++++----
1 file changed, 109 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
index f42ccc40ffa6..87804abd436f 100644
--- a/drivers/tty/serial/uartlite.c
+++ b/drivers/tty/serial/uartlite.c
@@ -8,6 +8,7 @@
#include <linux/platform_device.h>
#include <linux/module.h>
+#include <linux/bitfield.h>
#include <linux/console.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
@@ -60,9 +61,18 @@
static struct uart_port *console_port;
#endif
+/**
+ * struct uartlite_data: Driver private data
+ * reg_ops: Functions to read/write registers
+ * clk: Our parent clock, if present
+ * baud: The baud rate configured when this device was synthesized
+ * cflags: The cflags for parity and data bits
+ */
struct uartlite_data {
const struct uartlite_reg_ops *reg_ops;
struct clk *clk;
+ unsigned int baud;
+ tcflag_t cflags;
};
struct uartlite_reg_ops {
@@ -116,6 +126,8 @@ static inline void uart_out32(u32 val, u32 offset, struct uart_port *port)
static struct uart_port ulite_ports[ULITE_NR_UARTS];
+static struct uart_driver ulite_uart_driver;
+
/* ---------------------------------------------------------------------
* Core UART driver operations
*/
@@ -303,7 +315,42 @@ static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
unsigned long flags;
- unsigned int baud;
+ struct uartlite_data *pdata = port->private_data;
+ tcflag_t old_cflag;
+
+ /*
+ * If old is NULL then we're being set up for the first time
+ * (before any user has touched the termios), so don't warn
+ * about unsupported features.
+ */
+ if (old && termios->c_iflag & BRKINT)
+ dev_err_once(port->dev, "BREAK detection not supported\n");
+ termios->c_iflag &= ~BRKINT;
+
+ if (old && termios->c_cflag & CSTOPB && old)
+ dev_err_once(port->dev, "only one stop bit supported\n");
+ termios->c_cflag &= ~CSTOPB;
+
+ old_cflag = termios->c_cflag;
+ termios->c_cflag &= ~(PARENB | PARODD);
+ termios->c_cflag |= pdata->cflags & (PARENB | PARODD);
+ if (old && termios->c_cflag != old_cflag)
+ dev_err_once(port->dev, "only '%c' parity supported\n",
+ pdata->cflags & PARODD ? 'o' :
+ pdata->cflags & PARENB ? 'e' : 'n');
+
+ old_cflag = termios->c_cflag;
+ termios->c_cflag &= ~CSIZE;
+ termios->c_cflag |= pdata->cflags & CSIZE;
+ if (old && termios->c_cflag != old_cflag)
+ dev_err_once(port->dev, "only %d data bits supported\n",
+ FIELD_GET(CSIZE, pdata->cflags) + 5);
+
+ if (old &&
+ pdata->baud != uart_get_baud_rate(port, termios, old, 0, 460800))
+ dev_err_once(port->dev, "only %d baud supported\n",
+ pdata->baud);
+ tty_termios_encode_baud_rate(termios, pdata->baud, pdata->baud);
spin_lock_irqsave(&port->lock, flags);
@@ -326,8 +373,7 @@ static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
/* update timeout */
- baud = uart_get_baud_rate(port, termios, old, 0, 460800);
- uart_update_timeout(port, termios->c_cflag, baud);
+ uart_update_timeout(port, termios->c_cflag, pdata->baud);
spin_unlock_irqrestore(&port->lock, flags);
}
@@ -532,8 +578,6 @@ static int ulite_console_setup(struct console *co, char *options)
return uart_set_options(port, co, baud, parity, bits, flow);
}
-static struct uart_driver ulite_uart_driver;
-
static struct console ulite_console = {
.name = ULITE_NAME,
.write = ulite_console_write,
@@ -756,18 +800,72 @@ static int ulite_probe(struct platform_device *pdev)
struct uartlite_data *pdata;
int irq, ret;
int id = pdev->id;
-#ifdef CONFIG_OF
- const __be32 *prop;
- prop = of_get_property(pdev->dev.of_node, "port-number", NULL);
- if (prop)
- id = be32_to_cpup(prop);
-#endif
pdata = devm_kzalloc(&pdev->dev, sizeof(struct uartlite_data),
GFP_KERNEL);
if (!pdata)
return -ENOMEM;
+ if (IS_ENABLED(CONFIG_OF)) {
+ const char *prop;
+ struct device_node *np = pdev->dev.of_node;
+ u32 val;
+
+ prop = "port-number";
+ ret = of_property_read_u32(np, prop, &id);
+ if (ret && ret != -EINVAL)
+of_err:
+ return dev_err_probe(&pdev->dev, ret,
+ "could not read %s\n", prop);
+
+ prop = "current-speed";
+ ret = of_property_read_u32(np, prop, &pdata->baud);
+ if (ret)
+ goto of_err;
+
+ prop = "xlnx,use-parity";
+ ret = of_property_read_u32(np, prop, &val);
+ if (ret && ret != -EINVAL)
+ goto of_err;
+
+ if (val) {
+ prop = "xlnx,odd-parity";
+ ret = of_property_read_u32(np, prop, &val);
+ if (ret)
+ goto of_err;
+
+ if (val)
+ pdata->cflags |= PARODD;
+ pdata->cflags |= PARENB;
+ }
+
+ prop = "xlnx,data-bits";
+ ret = of_property_read_u32(np, prop, &val);
+ if (ret && ret != -EINVAL)
+ goto of_err;
+
+ switch (val) {
+ case 5:
+ pdata->cflags |= CS5;
+ break;
+ case 6:
+ pdata->cflags |= CS6;
+ break;
+ case 7:
+ pdata->cflags |= CS7;
+ break;
+ case 8:
+ pdata->cflags |= CS8;
+ break;
+ default:
+ return dev_err_probe(&pdev->dev, -EINVAL,
+ "bad data bits %d\n", val);
+ }
+ } else {
+ pdata->baud = 9600;
+ pdata->cflags = CS8;
+ }
+
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
--
2.25.1
