* [PATCH] gpio: add driver for SN74273 output expander
@ 2019-09-06 14:01 Ahmad Fatoum
2019-09-09 7:23 ` Sascha Hauer
0 siblings, 1 reply; 3+ messages in thread
From: Ahmad Fatoum @ 2019-09-06 14:01 UTC (permalink / raw)
To: barebox; +Cc: Ahmad Fatoum
The SN74273 is an octal D-Type Flip-Flop. When used as an output expander,
N existing output signals can be turned into (N-8)*8 outputs using
N-8 chips. Add driver to facilitate this.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
.../bindings/gpio/ti,74273-gpio.rst | 34 ++++
drivers/gpio/Kconfig | 5 +
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-74273.c | 183 ++++++++++++++++++
4 files changed, 223 insertions(+)
create mode 100644 Documentation/devicetree/bindings/gpio/ti,74273-gpio.rst
create mode 100644 drivers/gpio/gpio-74273.c
diff --git a/Documentation/devicetree/bindings/gpio/ti,74273-gpio.rst b/Documentation/devicetree/bindings/gpio/ti,74273-gpio.rst
new file mode 100644
index 000000000000..6fc001451c2f
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/ti,74273-gpio.rst
@@ -0,0 +1,34 @@
+74273 output expander driver
+============================
+
+Required properties:
+
+- ``compatible``: Should be ``"ti,74273-gpio"``
+- ``gpio-controller``: Marks the device node as a gpio controller.
+- ``#gpio-cells``: Should be two. The first cell is the pin number and
+ the second cell is used to specify the GPIO polarity:
+ ``0`` = Active High,
+ ``1`` = Active Low.
+- ``clk-gpios``: One GPIO per connected 74273 chip
+- ``data-gpios``: Eight GPIOs per connected 74273 (D-Pins)
+
+Optional properties:
+
+- ``ti,clk-pulse-width-ns``: minimal width of clock pulse for each chip.
+ If unspecified, ``<20>`` is used as default.
+
+Example::
+
+ sn74273-gpio {
+ compatible = "ti,74273-gpio";
+ gpio-controller;
+ #gpio-cells = <2>;
+
+ clk-gpios = <&gpio3 7 GPIO_ACTIVE_HIGH>, <&gpio3 8 GPIO_ACTIVE_HIGH>;
+ ti,clk-pulse-width-ns = <30>, <30>;
+ data-gpios = <&gpio3 21 GPIO_ACTIVE_LOW>, <&gpio3 22 GPIO_ACTIVE_LOW>,
+ <&gpio3 23 GPIO_ACTIVE_LOW>, <&gpio3 24 GPIO_ACTIVE_LOW>,
+ <&gpio3 25 GPIO_ACTIVE_LOW>, <&gpio3 26 GPIO_ACTIVE_LOW>,
+ <&gpio3 27 GPIO_ACTIVE_LOW>, <&gpio3 28 GPIO_ACTIVE_LOW>;
+ };
+
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 7a1503198b49..dd6e6dd0c1c8 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -145,6 +145,11 @@ config GPIO_SX150X
Say Y here to build support for the Semtec Sx150x I2C GPIO
expander chip.
+config GPIO_74273
+ bool "SN74273 output ports"
+ help
+ Say Y here to include a driver for the SN74273 as output expander
+
config GPIO_LIBFTDI1
bool "libftdi1 driver"
depends on SANDBOX
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 990df01788bc..ba818c7b94c0 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -21,3 +21,4 @@ obj-$(CONFIG_GPIO_TEGRA) += gpio-tegra.o
obj-$(CONFIG_GPIO_DESIGNWARE) += gpio-dw.o
obj-$(CONFIG_GPIO_SX150X) += gpio-sx150x.o
obj-$(CONFIG_GPIO_VF610) += gpio-vf610.o
+obj-$(CONFIG_GPIO_74273) += gpio-74273.o
diff --git a/drivers/gpio/gpio-74273.c b/drivers/gpio/gpio-74273.c
new file mode 100644
index 000000000000..873f523c1b0b
--- /dev/null
+++ b/drivers/gpio/gpio-74273.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017 Sascha Hauer, Pengutronix
+ * Copyright (c) 2019 Ahmad Fatoum, Pengutronix
+ */
+
+#include <common.h>
+#include <init.h>
+#include <malloc.h>
+#include <gpio.h>
+#include <of_gpio.h>
+#include <of.h>
+#include <clock.h>
+
+#define DEFAULT_DELAY_NS 20
+
+struct clk_gpio {
+ int desc;
+ u32 delay_ns;
+};
+
+struct sn74273 {
+ struct gpio_chip chip;
+ struct clk_gpio *clk_gpios;
+ int *data_gpios;
+ u8 *shadow;
+ unsigned n_ports;
+ unsigned n_pins;
+};
+
+static inline struct sn74273 *to_sn74273(struct gpio_chip *chip)
+{
+ return container_of(chip, struct sn74273, chip);
+}
+
+static void sn74273_gpio_set_value(struct gpio_chip *chip, unsigned gpio, int value)
+{
+ struct sn74273 *sn74273 = to_sn74273(chip);
+ unsigned port = gpio / 8;
+ unsigned pin = gpio % 8;
+ int i, j;
+ u8 val;
+
+ val = sn74273->shadow[port];
+ if (value)
+ val |= 1 << pin;
+ else
+ val &= ~(1 << pin);
+ sn74273->shadow[port] = val;
+
+ for (i = 0; i < sn74273->n_ports; i++) {
+ for (j = 0; j < sn74273->n_pins; j++) {
+ gpio_set_active(sn74273->data_gpios[j],
+ sn74273->shadow[i] & (1 << j));
+ }
+
+ ndelay(sn74273->clk_gpios[i].delay_ns);
+ gpio_set_active(sn74273->clk_gpios[i].desc, 1);
+ ndelay(sn74273->clk_gpios[i].delay_ns);
+ gpio_set_active(sn74273->clk_gpios[i].desc, 0);
+ }
+}
+
+static int sn74273_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
+{
+ struct sn74273 *sn74273 = to_sn74273(chip);
+ unsigned port = gpio / 8;
+ unsigned pin = gpio % 8;
+
+ return sn74273->shadow[port] & pin;
+}
+
+static int sn74273_gpio_direction_output(struct gpio_chip *chip,
+ unsigned offset, int value)
+{
+ sn74273_gpio_set_value(chip, offset, value);
+ return 0;
+}
+
+static int sn74273_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+ return GPIOF_DIR_OUT;
+}
+
+static struct gpio_ops sn74273_gpio_ops = {
+ .get = sn74273_gpio_get_value,
+ .set = sn74273_gpio_set_value,
+ .direction_output = sn74273_gpio_direction_output,
+ .get_direction = sn74273_gpio_get_direction,
+};
+
+static int sn74273_gpio_probe(struct device_d *dev)
+{
+ struct device_node *np = dev->device_node;
+ enum of_gpio_flags flags;
+ struct sn74273 *sn74273;
+ int i, ret;
+
+ sn74273 = xzalloc(sizeof(*sn74273));
+
+ sn74273->n_ports = of_gpio_named_count(np, "clk-gpios");
+ if (sn74273->n_ports < 0) {
+ dev_err(dev, "invalid or missing clk-gpios\n");
+ return -EINVAL;
+ }
+
+ sn74273->n_pins = of_gpio_named_count(np, "data-gpios");
+ if (sn74273->n_pins < 0) {
+ dev_err(dev, "invalid or missing data-gpios\n");
+ return -EINVAL;
+ }
+
+ sn74273->chip.base = -1;
+ sn74273->chip.ngpio = sn74273->n_ports * sn74273->n_pins;
+ sn74273->chip.dev = dev;
+ sn74273->chip.ops = &sn74273_gpio_ops;
+
+ sn74273->clk_gpios = xzalloc(sizeof(struct clk_gpio) * sn74273->n_ports);
+ sn74273->data_gpios = xzalloc(sizeof(int) * sn74273->n_pins);
+
+ for (i = 0; i < sn74273->n_ports; i++) {
+ struct clk_gpio *clk_gpio = &sn74273->clk_gpios[i];
+ clk_gpio->desc = of_get_named_gpio_flags(np, "clk-gpios",
+ i, &flags);
+ ret = gpio_request_one(clk_gpio->desc,
+ flags & OF_GPIO_ACTIVE_LOW ? GPIOF_ACTIVE_LOW : 0,
+ dev_name(dev));
+ if (ret) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "Cannot request gpio %d: %s\n", clk_gpio->desc,
+ strerror(-ret));
+ return ret;
+ }
+
+ gpio_direction_output(clk_gpio->desc, 0);
+
+ clk_gpio->delay_ns = DEFAULT_DELAY_NS;
+ of_property_read_u32_index(np, "ti,clk-pulse-width-ns",
+ i, &clk_gpio->delay_ns);
+ }
+
+ for (i = 0; i < sn74273->n_pins; i++) {
+ sn74273->data_gpios[i] = of_get_named_gpio_flags(np, "data-gpios",
+ i, &flags);
+ ret = gpio_request_one(sn74273->data_gpios[i],
+ flags & OF_GPIO_ACTIVE_LOW ? GPIOF_ACTIVE_LOW : 0,
+ dev_name(dev));
+ if (ret) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "Cannot request gpio %d: %s\n", sn74273->data_gpios[i],
+ strerror(-ret));
+ return ret;
+ }
+
+ gpio_direction_output(sn74273->data_gpios[i], 0);
+ }
+
+ sn74273->shadow = xzalloc(DIV_ROUND_UP(sn74273->n_pins, 8) * sn74273->n_ports);
+
+ ret = gpiochip_add(&sn74273->chip);
+ if (ret)
+ dev_err(dev, "cannot add 74273 GPIO chip: %s\n", strerror(-ret));
+
+ return ret;
+}
+
+static const struct of_device_id of_sn74273_gpio_leds_match[] = {
+ { .compatible = "ti,74273-gpio" },
+ { /* sentinel */ },
+};
+
+static struct driver_d sn74273_gpio_driver = {
+ .name = "74273-gpio",
+ .probe = sn74273_gpio_probe,
+ .of_compatible = DRV_OF_COMPAT(of_sn74273_gpio_leds_match),
+};
+
+static int sn74273_gpio_add(void)
+{
+ platform_driver_register(&sn74273_gpio_driver);
+ return 0;
+}
+postcore_initcall(sn74273_gpio_add);
--
2.23.0
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] gpio: add driver for SN74273 output expander
2019-09-06 14:01 [PATCH] gpio: add driver for SN74273 output expander Ahmad Fatoum
@ 2019-09-09 7:23 ` Sascha Hauer
2019-09-17 9:22 ` Ahmad Fatoum
0 siblings, 1 reply; 3+ messages in thread
From: Sascha Hauer @ 2019-09-09 7:23 UTC (permalink / raw)
To: Ahmad Fatoum; +Cc: barebox
On Fri, Sep 06, 2019 at 04:01:27PM +0200, Ahmad Fatoum wrote:
> The SN74273 is an octal D-Type Flip-Flop. When used as an output expander,
> N existing output signals can be turned into (N-8)*8 outputs using
> N-8 chips. Add driver to facilitate this.
The reason I haven't mainlined this driver when writing it was that
Linux also has a driver for the 74273, but in a completely different
setup. In the Linux driver the 74273 is assumed to have its inputs on
the data bus together with a separate address decoder.
The chip in this driver here instead is connected via GPIO pins. For
Using flipflops as GPIO expanders there a myriads of different ways to
implement, so I have my doubts how useful it is to even try to put them
in a generic driver.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] gpio: add driver for SN74273 output expander
2019-09-09 7:23 ` Sascha Hauer
@ 2019-09-17 9:22 ` Ahmad Fatoum
0 siblings, 0 replies; 3+ messages in thread
From: Ahmad Fatoum @ 2019-09-17 9:22 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
On 9/9/19 9:23 AM, Sascha Hauer wrote:
> On Fri, Sep 06, 2019 at 04:01:27PM +0200, Ahmad Fatoum wrote:
>> The SN74273 is an octal D-Type Flip-Flop. When used as an output expander,
>> N existing output signals can be turned into (N-8)*8 outputs using
>> N-8 chips. Add driver to facilitate this.
>
> The reason I haven't mainlined this driver when writing it was that
> Linux also has a driver for the 74273, but in a completely different
> setup. In the Linux driver the 74273 is assumed to have its inputs on
> the data bus together with a separate address decoder.
> The chip in this driver here instead is connected via GPIO pins. For
> Using flipflops as GPIO expanders there a myriads of different ways to
> implement, so I have my doubts how useful it is to even try to put them
> in a generic driver.
FTR: I talked this over with Sascha. As I understood, the main issue is
with reserving a fairly generic "ti,74273-gpio" compatible with what is
a very special way of using these flip flops. We could however get it in
with a different proprietary compatible. I might revisit this in future
along with a kernel driver, but please dismiss for now.
>
> Sascha
>
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 3+ messages in thread
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