* [PATCH v10 1/6] serial: sc16is7xx: fix broken port 0 uart init
[not found] <20230807214556.540627-1-hugo@hugovil.com>
@ 2023-08-07 21:45 ` Hugo Villeneuve
2023-08-07 21:45 ` [PATCH v10 3/6] dt-bindings: sc16is7xx: Add property to change GPIO function Hugo Villeneuve
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Hugo Villeneuve @ 2023-08-07 21:45 UTC (permalink / raw)
To: gregkh, robh+dt, krzysztof.kozlowski+dt, conor+dt, jirislaby,
jringle, tomasz.mon, l.perczak
Cc: linux-serial, devicetree, linux-kernel, hugo, linux-gpio,
Hugo Villeneuve, stable, Ilpo Järvinen, Lech Perczak
From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
The sc16is7xx_config_rs485() function is called only for the second
port (index 1, channel B), causing initialization problems for the
first port.
For the sc16is7xx driver, port->membase and port->mapbase are not set,
and their default values are 0. And we set port->iobase to the device
index. This means that when the first device is registered using the
uart_add_one_port() function, the following values will be in the port
structure:
port->membase = 0
port->mapbase = 0
port->iobase = 0
Therefore, the function uart_configure_port() in serial_core.c will
exit early because of the following check:
/*
* If there isn't a port here, don't do anything further.
*/
if (!port->iobase && !port->mapbase && !port->membase)
return;
Typically, I2C and SPI drivers do not set port->membase and
port->mapbase.
The max310x driver sets port->membase to ~0 (all ones). By
implementing the same change in this driver, uart_configure_port() is
now correctly executed for all ports.
Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: <stable@vger.kernel.org>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
---
drivers/tty/serial/sc16is7xx.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 18a48ce052c2..ffe817309413 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1438,6 +1438,12 @@ static int sc16is7xx_probe(struct device *dev,
s->p[i].port.fifosize = SC16IS7XX_FIFO_SIZE;
s->p[i].port.flags = UPF_FIXED_TYPE | UPF_LOW_LATENCY;
s->p[i].port.iobase = i;
+ /*
+ * Use all ones as membase to make sure uart_configure_port() in
+ * serial_core.c does not abort for SPI/I2C devices where the
+ * membase address is not applicable.
+ */
+ s->p[i].port.membase = (void __iomem *)~0;
s->p[i].port.iotype = UPIO_PORT;
s->p[i].port.uartclk = freq;
s->p[i].port.rs485_config = sc16is7xx_config_rs485;
--
2.30.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v10 3/6] dt-bindings: sc16is7xx: Add property to change GPIO function
[not found] <20230807214556.540627-1-hugo@hugovil.com>
2023-08-07 21:45 ` [PATCH v10 1/6] serial: sc16is7xx: fix broken port 0 uart init Hugo Villeneuve
@ 2023-08-07 21:45 ` Hugo Villeneuve
2023-08-17 18:02 ` Rob Herring
2023-08-07 21:45 ` [PATCH v10 4/6] serial: sc16is7xx: fix regression with GPIO configuration Hugo Villeneuve
2023-08-07 21:45 ` [PATCH v10 5/6] serial: sc16is7xx: fix bug when first setting GPIO direction Hugo Villeneuve
3 siblings, 1 reply; 6+ messages in thread
From: Hugo Villeneuve @ 2023-08-07 21:45 UTC (permalink / raw)
To: gregkh, robh+dt, krzysztof.kozlowski+dt, conor+dt, jirislaby,
jringle, tomasz.mon, l.perczak
Cc: linux-serial, devicetree, linux-kernel, hugo, linux-gpio,
Hugo Villeneuve, stable, Conor Dooley, Lech Perczak
From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Some variants in this series of UART controllers have GPIO pins that
are shared between GPIO and modem control lines.
The pin mux mode (GPIO or modem control lines) can be set for each
ports (channels) supported by the variant.
This adds a property to the device tree to set the GPIO pin mux to
modem control lines on selected ports if needed.
Cc: <stable@vger.kernel.org> # 6.1.x
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
---
.../bindings/serial/nxp,sc16is7xx.txt | 46 +++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/Documentation/devicetree/bindings/serial/nxp,sc16is7xx.txt b/Documentation/devicetree/bindings/serial/nxp,sc16is7xx.txt
index 0fa8e3e43bf8..1a7e4bff0456 100644
--- a/Documentation/devicetree/bindings/serial/nxp,sc16is7xx.txt
+++ b/Documentation/devicetree/bindings/serial/nxp,sc16is7xx.txt
@@ -23,6 +23,9 @@ Optional properties:
1 = active low.
- irda-mode-ports: An array that lists the indices of the port that
should operate in IrDA mode.
+- nxp,modem-control-line-ports: An array that lists the indices of the port that
+ should have shared GPIO lines configured as
+ modem control lines.
Example:
sc16is750: sc16is750@51 {
@@ -35,6 +38,26 @@ Example:
#gpio-cells = <2>;
};
+ sc16is752: sc16is752@53 {
+ compatible = "nxp,sc16is752";
+ reg = <0x53>;
+ clocks = <&clk20m>;
+ interrupt-parent = <&gpio3>;
+ interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
+ nxp,modem-control-line-ports = <1>; /* Port 1 as modem control lines */
+ gpio-controller; /* Port 0 as GPIOs */
+ #gpio-cells = <2>;
+ };
+
+ sc16is752: sc16is752@54 {
+ compatible = "nxp,sc16is752";
+ reg = <0x54>;
+ clocks = <&clk20m>;
+ interrupt-parent = <&gpio3>;
+ interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
+ nxp,modem-control-line-ports = <0 1>; /* Ports 0 and 1 as modem control lines */
+ };
+
* spi as bus
Required properties:
@@ -59,6 +82,9 @@ Optional properties:
1 = active low.
- irda-mode-ports: An array that lists the indices of the port that
should operate in IrDA mode.
+- nxp,modem-control-line-ports: An array that lists the indices of the port that
+ should have shared GPIO lines configured as
+ modem control lines.
Example:
sc16is750: sc16is750@0 {
@@ -70,3 +96,23 @@ Example:
gpio-controller;
#gpio-cells = <2>;
};
+
+ sc16is752: sc16is752@1 {
+ compatible = "nxp,sc16is752";
+ reg = <1>;
+ clocks = <&clk20m>;
+ interrupt-parent = <&gpio3>;
+ interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
+ nxp,modem-control-line-ports = <1>; /* Port 1 as modem control lines */
+ gpio-controller; /* Port 0 as GPIOs */
+ #gpio-cells = <2>;
+ };
+
+ sc16is752: sc16is752@2 {
+ compatible = "nxp,sc16is752";
+ reg = <2>;
+ clocks = <&clk20m>;
+ interrupt-parent = <&gpio3>;
+ interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
+ nxp,modem-control-line-ports = <0 1>; /* Ports 0 and 1 as modem control lines */
+ };
--
2.30.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v10 3/6] dt-bindings: sc16is7xx: Add property to change GPIO function
2023-08-07 21:45 ` [PATCH v10 3/6] dt-bindings: sc16is7xx: Add property to change GPIO function Hugo Villeneuve
@ 2023-08-17 18:02 ` Rob Herring
0 siblings, 0 replies; 6+ messages in thread
From: Rob Herring @ 2023-08-17 18:02 UTC (permalink / raw)
To: Hugo Villeneuve
Cc: linux-serial, gregkh, jringle, devicetree, Conor Dooley,
Lech Perczak, linux-kernel, tomasz.mon, l.perczak,
Hugo Villeneuve, linux-gpio, jirislaby, stable, robh+dt,
krzysztof.kozlowski+dt, conor+dt
On Mon, 07 Aug 2023 17:45:53 -0400, Hugo Villeneuve wrote:
> From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
>
> Some variants in this series of UART controllers have GPIO pins that
> are shared between GPIO and modem control lines.
>
> The pin mux mode (GPIO or modem control lines) can be set for each
> ports (channels) supported by the variant.
>
> This adds a property to the device tree to set the GPIO pin mux to
> modem control lines on selected ports if needed.
>
> Cc: <stable@vger.kernel.org> # 6.1.x
> Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
> ---
> .../bindings/serial/nxp,sc16is7xx.txt | 46 +++++++++++++++++++
> 1 file changed, 46 insertions(+)
>
Acked-by: Rob Herring <robh@kernel.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v10 4/6] serial: sc16is7xx: fix regression with GPIO configuration
[not found] <20230807214556.540627-1-hugo@hugovil.com>
2023-08-07 21:45 ` [PATCH v10 1/6] serial: sc16is7xx: fix broken port 0 uart init Hugo Villeneuve
2023-08-07 21:45 ` [PATCH v10 3/6] dt-bindings: sc16is7xx: Add property to change GPIO function Hugo Villeneuve
@ 2023-08-07 21:45 ` Hugo Villeneuve
2023-08-17 18:01 ` Rob Herring
2023-08-07 21:45 ` [PATCH v10 5/6] serial: sc16is7xx: fix bug when first setting GPIO direction Hugo Villeneuve
3 siblings, 1 reply; 6+ messages in thread
From: Hugo Villeneuve @ 2023-08-07 21:45 UTC (permalink / raw)
To: gregkh, robh+dt, krzysztof.kozlowski+dt, conor+dt, jirislaby,
jringle, tomasz.mon, l.perczak
Cc: linux-serial, devicetree, linux-kernel, hugo, linux-gpio,
Hugo Villeneuve, stable, Andy Shevchenko, Lech Perczak
From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Commit 679875d1d880 ("sc16is7xx: Separate GPIOs from modem control lines")
and commit 21144bab4f11 ("sc16is7xx: Handle modem status lines")
changed the function of the GPIOs pins to act as modem control
lines without any possibility of selecting GPIO function.
As a consequence, applications that depends on GPIO lines configured
by default as GPIO pins no longer work as expected.
Also, the change to select modem control lines function was done only
for channel A of dual UART variants (752/762). This was not documented
in the log message.
Allow to specify GPIO or modem control line function in the device
tree, and for each of the ports (A or B).
Do so by using the new device-tree property named
"nxp,modem-control-line-ports" (property added in separate patch).
When registering GPIO chip controller, mask-out GPIO pins declared as
modem control lines according to this new DT property.
Fixes: 679875d1d880 ("sc16is7xx: Separate GPIOs from modem control lines")
Fixes: 21144bab4f11 ("sc16is7xx: Handle modem status lines")
Cc: <stable@vger.kernel.org>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
---
drivers/tty/serial/sc16is7xx.c | 143 +++++++++++++++++++++++++--------
1 file changed, 108 insertions(+), 35 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 93b4137daa8b..b45e34e3910d 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -236,7 +236,8 @@
/* IOControl register bits (Only 750/760) */
#define SC16IS7XX_IOCONTROL_LATCH_BIT (1 << 0) /* Enable input latching */
-#define SC16IS7XX_IOCONTROL_MODEM_BIT (1 << 1) /* Enable GPIO[7:4] as modem pins */
+#define SC16IS7XX_IOCONTROL_MODEM_A_BIT (1 << 1) /* Enable GPIO[7:4] as modem A pins */
+#define SC16IS7XX_IOCONTROL_MODEM_B_BIT (1 << 2) /* Enable GPIO[3:0] as modem B pins */
#define SC16IS7XX_IOCONTROL_SRESET_BIT (1 << 3) /* Software Reset */
/* EFCR register bits */
@@ -301,12 +302,12 @@
/* Misc definitions */
#define SC16IS7XX_FIFO_SIZE (64)
#define SC16IS7XX_REG_SHIFT 2
+#define SC16IS7XX_GPIOS_PER_BANK 4
struct sc16is7xx_devtype {
char name[10];
int nr_gpio;
int nr_uart;
- int has_mctrl;
};
#define SC16IS7XX_RECONF_MD (1 << 0)
@@ -336,7 +337,9 @@ struct sc16is7xx_port {
struct clk *clk;
#ifdef CONFIG_GPIOLIB
struct gpio_chip gpio;
+ unsigned long gpio_valid_mask;
#endif
+ u8 mctrl_mask;
unsigned char buf[SC16IS7XX_FIFO_SIZE];
struct kthread_worker kworker;
struct task_struct *kworker_task;
@@ -447,35 +450,30 @@ static const struct sc16is7xx_devtype sc16is74x_devtype = {
.name = "SC16IS74X",
.nr_gpio = 0,
.nr_uart = 1,
- .has_mctrl = 0,
};
static const struct sc16is7xx_devtype sc16is750_devtype = {
.name = "SC16IS750",
- .nr_gpio = 4,
+ .nr_gpio = 8,
.nr_uart = 1,
- .has_mctrl = 1,
};
static const struct sc16is7xx_devtype sc16is752_devtype = {
.name = "SC16IS752",
- .nr_gpio = 0,
+ .nr_gpio = 8,
.nr_uart = 2,
- .has_mctrl = 1,
};
static const struct sc16is7xx_devtype sc16is760_devtype = {
.name = "SC16IS760",
- .nr_gpio = 4,
+ .nr_gpio = 8,
.nr_uart = 1,
- .has_mctrl = 1,
};
static const struct sc16is7xx_devtype sc16is762_devtype = {
.name = "SC16IS762",
- .nr_gpio = 0,
+ .nr_gpio = 8,
.nr_uart = 2,
- .has_mctrl = 1,
};
static bool sc16is7xx_regmap_volatile(struct device *dev, unsigned int reg)
@@ -1350,8 +1348,98 @@ static int sc16is7xx_gpio_direction_output(struct gpio_chip *chip,
return 0;
}
+
+static int sc16is7xx_gpio_init_valid_mask(struct gpio_chip *chip,
+ unsigned long *valid_mask,
+ unsigned int ngpios)
+{
+ struct sc16is7xx_port *s = gpiochip_get_data(chip);
+
+ *valid_mask = s->gpio_valid_mask;
+
+ return 0;
+}
+
+static int sc16is7xx_setup_gpio_chip(struct sc16is7xx_port *s)
+{
+ struct device *dev = s->p[0].port.dev;
+
+ if (!s->devtype->nr_gpio)
+ return 0;
+
+ switch (s->mctrl_mask) {
+ case 0:
+ s->gpio_valid_mask = GENMASK(7, 0);
+ break;
+ case SC16IS7XX_IOCONTROL_MODEM_A_BIT:
+ s->gpio_valid_mask = GENMASK(3, 0);
+ break;
+ case SC16IS7XX_IOCONTROL_MODEM_B_BIT:
+ s->gpio_valid_mask = GENMASK(7, 4);
+ break;
+ default:
+ break;
+ }
+
+ if (s->gpio_valid_mask == 0)
+ return 0;
+
+ s->gpio.owner = THIS_MODULE;
+ s->gpio.parent = dev;
+ s->gpio.label = dev_name(dev);
+ s->gpio.init_valid_mask = sc16is7xx_gpio_init_valid_mask;
+ s->gpio.direction_input = sc16is7xx_gpio_direction_input;
+ s->gpio.get = sc16is7xx_gpio_get;
+ s->gpio.direction_output = sc16is7xx_gpio_direction_output;
+ s->gpio.set = sc16is7xx_gpio_set;
+ s->gpio.base = -1;
+ s->gpio.ngpio = s->devtype->nr_gpio;
+ s->gpio.can_sleep = 1;
+
+ return gpiochip_add_data(&s->gpio, s);
+}
#endif
+/*
+ * Configure ports designated to operate as modem control lines.
+ */
+static int sc16is7xx_setup_mctrl_ports(struct sc16is7xx_port *s)
+{
+ int i;
+ int ret;
+ int count;
+ u32 mctrl_port[2];
+ struct device *dev = s->p[0].port.dev;
+
+ count = device_property_count_u32(dev, "nxp,modem-control-line-ports");
+ if (count < 0 || count > ARRAY_SIZE(mctrl_port))
+ return 0;
+
+ ret = device_property_read_u32_array(dev, "nxp,modem-control-line-ports",
+ mctrl_port, count);
+ if (ret)
+ return ret;
+
+ s->mctrl_mask = 0;
+
+ for (i = 0; i < count; i++) {
+ /* Use GPIO lines as modem control lines */
+ if (mctrl_port[i] == 0)
+ s->mctrl_mask |= SC16IS7XX_IOCONTROL_MODEM_A_BIT;
+ else if (mctrl_port[i] == 1)
+ s->mctrl_mask |= SC16IS7XX_IOCONTROL_MODEM_B_BIT;
+ }
+
+ if (s->mctrl_mask)
+ regmap_update_bits(
+ s->regmap,
+ SC16IS7XX_IOCONTROL_REG << SC16IS7XX_REG_SHIFT,
+ SC16IS7XX_IOCONTROL_MODEM_A_BIT |
+ SC16IS7XX_IOCONTROL_MODEM_B_BIT, s->mctrl_mask);
+
+ return 0;
+}
+
static const struct serial_rs485 sc16is7xx_rs485_supported = {
.flags = SER_RS485_ENABLED | SER_RS485_RTS_AFTER_SEND,
.delay_rts_before_send = 1,
@@ -1464,12 +1552,6 @@ static int sc16is7xx_probe(struct device *dev,
SC16IS7XX_EFCR_RXDISABLE_BIT |
SC16IS7XX_EFCR_TXDISABLE_BIT);
- /* Use GPIO lines as modem status registers */
- if (devtype->has_mctrl)
- sc16is7xx_port_write(&s->p[i].port,
- SC16IS7XX_IOCONTROL_REG,
- SC16IS7XX_IOCONTROL_MODEM_BIT);
-
/* Initialize kthread work structs */
kthread_init_work(&s->p[i].tx_work, sc16is7xx_tx_proc);
kthread_init_work(&s->p[i].reg_work, sc16is7xx_reg_proc);
@@ -1507,23 +1589,14 @@ static int sc16is7xx_probe(struct device *dev,
s->p[u].irda_mode = true;
}
+ ret = sc16is7xx_setup_mctrl_ports(s);
+ if (ret)
+ goto out_ports;
+
#ifdef CONFIG_GPIOLIB
- if (devtype->nr_gpio) {
- /* Setup GPIO cotroller */
- s->gpio.owner = THIS_MODULE;
- s->gpio.parent = dev;
- s->gpio.label = dev_name(dev);
- s->gpio.direction_input = sc16is7xx_gpio_direction_input;
- s->gpio.get = sc16is7xx_gpio_get;
- s->gpio.direction_output = sc16is7xx_gpio_direction_output;
- s->gpio.set = sc16is7xx_gpio_set;
- s->gpio.base = -1;
- s->gpio.ngpio = devtype->nr_gpio;
- s->gpio.can_sleep = 1;
- ret = gpiochip_add_data(&s->gpio, s);
- if (ret)
- goto out_ports;
- }
+ ret = sc16is7xx_setup_gpio_chip(s);
+ if (ret)
+ goto out_ports;
#endif
/*
@@ -1546,7 +1619,7 @@ static int sc16is7xx_probe(struct device *dev,
return 0;
#ifdef CONFIG_GPIOLIB
- if (devtype->nr_gpio)
+ if (s->gpio_valid_mask)
gpiochip_remove(&s->gpio);
#endif
@@ -1570,7 +1643,7 @@ static void sc16is7xx_remove(struct device *dev)
int i;
#ifdef CONFIG_GPIOLIB
- if (s->devtype->nr_gpio)
+ if (s->gpio_valid_mask)
gpiochip_remove(&s->gpio);
#endif
--
2.30.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v10 4/6] serial: sc16is7xx: fix regression with GPIO configuration
2023-08-07 21:45 ` [PATCH v10 4/6] serial: sc16is7xx: fix regression with GPIO configuration Hugo Villeneuve
@ 2023-08-17 18:01 ` Rob Herring
0 siblings, 0 replies; 6+ messages in thread
From: Rob Herring @ 2023-08-17 18:01 UTC (permalink / raw)
To: Hugo Villeneuve
Cc: gregkh, krzysztof.kozlowski+dt, conor+dt, jirislaby, jringle,
tomasz.mon, l.perczak, linux-serial, devicetree, linux-kernel,
linux-gpio, Hugo Villeneuve, stable, Andy Shevchenko,
Lech Perczak
On Mon, Aug 07, 2023 at 05:45:54PM -0400, Hugo Villeneuve wrote:
> From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
>
> Commit 679875d1d880 ("sc16is7xx: Separate GPIOs from modem control lines")
> and commit 21144bab4f11 ("sc16is7xx: Handle modem status lines")
> changed the function of the GPIOs pins to act as modem control
> lines without any possibility of selecting GPIO function.
>
> As a consequence, applications that depends on GPIO lines configured
> by default as GPIO pins no longer work as expected.
>
> Also, the change to select modem control lines function was done only
> for channel A of dual UART variants (752/762). This was not documented
> in the log message.
>
> Allow to specify GPIO or modem control line function in the device
> tree, and for each of the ports (A or B).
>
> Do so by using the new device-tree property named
> "nxp,modem-control-line-ports" (property added in separate patch).
>
> When registering GPIO chip controller, mask-out GPIO pins declared as
> modem control lines according to this new DT property.
>
> Fixes: 679875d1d880 ("sc16is7xx: Separate GPIOs from modem control lines")
> Fixes: 21144bab4f11 ("sc16is7xx: Handle modem status lines")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
> Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
> ---
> drivers/tty/serial/sc16is7xx.c | 143 +++++++++++++++++++++++++--------
> 1 file changed, 108 insertions(+), 35 deletions(-)
Acked-by: Rob Herring <robh@kernel.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v10 5/6] serial: sc16is7xx: fix bug when first setting GPIO direction
[not found] <20230807214556.540627-1-hugo@hugovil.com>
` (2 preceding siblings ...)
2023-08-07 21:45 ` [PATCH v10 4/6] serial: sc16is7xx: fix regression with GPIO configuration Hugo Villeneuve
@ 2023-08-07 21:45 ` Hugo Villeneuve
3 siblings, 0 replies; 6+ messages in thread
From: Hugo Villeneuve @ 2023-08-07 21:45 UTC (permalink / raw)
To: gregkh, robh+dt, krzysztof.kozlowski+dt, conor+dt, jirislaby,
jringle, tomasz.mon, l.perczak
Cc: linux-serial, devicetree, linux-kernel, hugo, linux-gpio,
Hugo Villeneuve, stable, Lech Perczak
From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
When configuring a pin as an output pin with a value of logic 0, we
end up as having a value of logic 1 on the output pin. Setting a
logic 0 a second time (or more) after that will correctly output a
logic 0 on the output pin.
By default, all GPIO pins are configured as inputs. When we enter
sc16is7xx_gpio_direction_output() for the first time, we first set the
desired value in IOSTATE, and then we configure the pin as an output.
The datasheet states that writing to IOSTATE register will trigger a
transfer of the value to the I/O pin configured as output, so if the
pin is configured as an input, nothing will be transferred.
Therefore, set the direction first in IODIR, and then set the desired
value in IOSTATE.
This is what is done in NXP application note AN10587.
Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: <stable@vger.kernel.org>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
---
drivers/tty/serial/sc16is7xx.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index b45e34e3910d..cfc88959b2f7 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1342,9 +1342,18 @@ static int sc16is7xx_gpio_direction_output(struct gpio_chip *chip,
state |= BIT(offset);
else
state &= ~BIT(offset);
- sc16is7xx_port_write(port, SC16IS7XX_IOSTATE_REG, state);
+
+ /*
+ * If we write IOSTATE first, and then IODIR, the output value is not
+ * transferred to the corresponding I/O pin.
+ * The datasheet states that each register bit will be transferred to
+ * the corresponding I/O pin programmed as output when writing to
+ * IOSTATE. Therefore, configure direction first with IODIR, and then
+ * set value after with IOSTATE.
+ */
sc16is7xx_port_update(port, SC16IS7XX_IODIR_REG, BIT(offset),
BIT(offset));
+ sc16is7xx_port_write(port, SC16IS7XX_IOSTATE_REG, state);
return 0;
}
--
2.30.2
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