On 2021/12/21 15:34, Greg Kroah-Hartman wrote:
[ EXTERNAL EMAIL ]
On Tue, Dec 21, 2021 at 03:16:34PM +0800, Yu Tu wrote:
The S4 SoC on-chip UART uses a 12M clock as the clock source for
calculating the baud rate of the UART. But previously, chips used 24M or
other clock sources. So add this change. The specific clock source is
determined by chip design.
Signed-off-by: Yu Tu <yu.tu@xxxxxxxxxxx>
---
drivers/tty/serial/meson_uart.c | 62 +++++++++++++++++++++++++++++----
1 file changed, 55 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 69450a461c48..557c24d954a2 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -19,6 +19,7 @@
#include <linux/serial_core.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
+#include <linux/of_device.h>
/* Register offsets */
#define AML_UART_WFIFO 0x00
@@ -68,6 +69,8 @@
#define AML_UART_BAUD_MASK 0x7fffff
#define AML_UART_BAUD_USE BIT(23)
#define AML_UART_BAUD_XTAL BIT(24)
+#define AML_UART_BAUD_XTAL_TICK BIT(26)
+#define AML_UART_BAUD_XTAL_DIV2 BIT(27)
#define AML_UART_PORT_NUM 12
#define AML_UART_PORT_OFFSET 6
@@ -80,6 +83,11 @@ static struct uart_driver meson_uart_driver;
static struct uart_port *meson_ports[AML_UART_PORT_NUM];
+struct meson_uart_data {
+ /*A clock source that calculates baud rates*/
Please use spaces in your comments.
I will correct this mistake in the next patch.
+ unsigned int xtal_tick_en;
What is "_en" for?
"enabled"?
Spell it out please.
You're right.I will correct as you suggested.
And why an unsigned int for a boolean flag?
It is my thoughtless, I will correct.
+};
+
static void meson_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}
@@ -294,16 +302,29 @@ static int meson_uart_startup(struct uart_port *port)
static void meson_uart_change_speed(struct uart_port *port, unsigned long baud)
{
+ struct meson_uart_data *uart_data = port->private_data;
u32 val;
while (!meson_uart_tx_empty(port))
cpu_relax();
+ val = readl_relaxed(port->membase + AML_UART_REG5);
+ val &= ~AML_UART_BAUD_MASK;
+
if (port->uartclk == 24000000) {
- val = ((port->uartclk / 3) / baud) - 1;
- val |= AML_UART_BAUD_XTAL;
+ if (uart_data->xtal_tick_en) {
+ val = (port->uartclk / 2 + baud / 2) / baud - 1;
+ val |= (AML_UART_BAUD_XTAL | AML_UART_BAUD_XTAL_DIV2);
+ } else {
+ val = ((port->uartclk / 3) + baud / 2) / baud - 1;
+ val &= (~(AML_UART_BAUD_XTAL_TICK |
+ AML_UART_BAUD_XTAL_DIV2));
+ val |= AML_UART_BAUD_XTAL;
+ }
} else {
val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;
+ val &= (~(AML_UART_BAUD_XTAL | AML_UART_BAUD_XTAL_TICK |
+ AML_UART_BAUD_XTAL_DIV2));
}
val |= AML_UART_BAUD_USE;
writel(val, port->membase + AML_UART_REG5);
@@ -714,6 +735,7 @@ static int meson_uart_probe(struct platform_device *pdev)
{
struct resource *res_mem, *res_irq;
struct uart_port *port;
+ struct meson_uart_data *uart_data;
int ret = 0;
int id = -1;
@@ -729,6 +751,10 @@ static int meson_uart_probe(struct platform_device *pdev)
}
}
+ uart_data = of_device_get_match_data(&pdev->dev);
+ if (!uart_data)
+ return -EINVAL;
Wrong spacing.
Always use checkpatch.pl on your patches before sending them out.
Sorry, this is a rookie mistake.But I did check it locally before
sending it. I will follow your advice strictly later.
And did you just break existing systems? Do you know if all older ones
will still work with that call?
It does affect older systems, but the new and older baud rates are not
the same. I checked the documents before I made any changes. So this
change is compatible with the older.
+
if (pdev->id < 0 || pdev->id >= AML_UART_PORT_NUM)
return -EINVAL;
@@ -770,6 +796,7 @@ static int meson_uart_probe(struct platform_device *pdev)
port->x_char = 0;
port->ops = &meson_uart_ops;
port->fifosize = 64;
+ port->private_data = uart_data;
meson_ports[pdev->id] = port;
platform_set_drvdata(pdev, port);
@@ -798,14 +825,35 @@ static int meson_uart_remove(struct platform_device *pdev)
return 0;
}
+static const struct meson_uart_data meson_uart_data = {
+ .xtal_tick_en = 0,
+};
+
+static const struct meson_uart_data s4_meson_uart_data = {
+ .xtal_tick_en = 1,
+};
As your whole structure just has one bit, why not just use that as the
data value, instead of a structure? No need to be complex here at all.
It is my thoughtless, I will correct.
thanks,
greg k-h
