XRA1403,gpio - add XRA1403 gpio expander driver
Subsystems (2)
cover XRA1403,gpio - add XRA1403 gpio expander driver
The patchset will add a driver to support basic functionality for XRA1403 device. Features supported:
- configure gpin as input/out
- get/set gpio status
Documentation: A gpio-xra1403.txt file was added to document the DTS
bindings related to driver.
Testing:
1. XRA1403 connected to iMX53 MCU
2. Export gpio from userspace
3. Verify that corresponding gpio directories are created in /sys/class/gpio/gpioXX
4. Export gpios from first and second bank as output
5. Set the output gpio pin to high/low and verify with the oscilloscope that gpio status is according with the configured value.
Nandor Han (3):
gpio - Add EXAR XRA1403 SPI GPIO expander driver doc,dts - add XRA1403 DTS binding documentation Add XRA1403 support to MAINTAINERS file
.../devicetree/bindings/gpio/gpio-xra1403.txt | 37 +++ .../devicetree/bindings/vendor-prefixes.txt | 1 + MAINTAINERS | 8 + drivers/gpio/Kconfig | 5 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-xra1403.c | 252 +++++++++++++++++++++ 6 files changed, 304 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/gpio-xra1403.txt create mode 100644 drivers/gpio/gpio-xra1403.c
Signature · 1 line
2.10.1
PATCH 1/3 gpio - Add EXAR XRA1403 SPI GPIO expander driver
This is a simple driver that provides a /sys/class/gpio interface for controlling and configuring the GPIO lines. It does not provide support for chip select or interrupts.
--- .../devicetree/bindings/vendor-prefixes.txt | 1 + drivers/gpio/Kconfig | 5 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-xra1403.c | 252 +++++++++++++++++++++ 4 files changed, 259 insertions(+) create mode 100644 drivers/gpio/gpio-xra1403.c
Documentation/devicetree/bindings/vendor-prefixes.txt +1 -0
@@ -103,6 +103,7 @@ ettus NI Ettus Research eukrea Eukréa Electromatique everest Everest Semiconductor Co. Ltd. everspin Everspin Technologies, Inc. +exar Exar Corporation excito Excito ezchip EZchip Semiconductor faraday Faraday Technology Corporation
drivers/gpio/Kconfig +5 -0
@@ -1208,6 +1208,11 @@ config GPIO_PISOSR GPIO driver for SPI compatible parallel-in/serial-out shift registers. These are input only devices. +config GPIO_XRA1403 + tristate "EXAR XRA1403 16-bit GPIO expander" + help + GPIO driver for EXAR XRA1403 16-bit SPI-based GPIO expander. + endmenu menu "SPI or I2C GPIO expanders"
drivers/gpio/Makefile +1 -0
@@ -139,6 +139,7 @@ obj-$(CONFIG_GPIO_XGENE) += gpio-xgene.o obj-$(CONFIG_GPIO_XGENE_SB) += gpio-xgene-sb.o obj-$(CONFIG_GPIO_XILINX) += gpio-xilinx.o obj-$(CONFIG_GPIO_XLP) += gpio-xlp.o +obj-$(CONFIG_GPIO_XRA1403) += gpio-xra1403.o obj-$(CONFIG_GPIO_XTENSA) += gpio-xtensa.o obj-$(CONFIG_GPIO_ZEVIO) += gpio-zevio.o obj-$(CONFIG_GPIO_ZYNQ) += gpio-zynq.o
drivers/gpio/gpio-xra1403.c new file +252 -0
252 lines not on this page · raw message
Signature · 6 lines
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Re: [PATCH 1/3] gpio - Add EXAR XRA1403 SPI GPIO expander driver
Quoted 2 lines · Nandor Han
This is a simple driver that provides a
/sys/class/gpiointerface for controlling and configuring the GPIO lines.
Use the gpio tools in tools/gpio, use the characcter device. Do not use sysfs. Change this to reference the tools.
Quoted 4 lines
It does not provide support for chip select or interrupts.
Signed-off-by Nandor Han <[email protected]>Signed-off-by Semi Malinen <[email protected]>
(...)
Quoted 1 line
+exar Exar Corporation
Send this as a separate patch to the DT bindings maintainer (Rob Herring.)
Quoted 6 lines
drivers/gpio/gpio-xra1403.c new file +6
-0+static int xra1403_get_byte (struct xra1403 *xra,unsigned int addr) +{ +return spi_w8r8 (xra->spi,XRA_READ | (addr <<1 )); +} + +static int xra1403_get_bit(struct xra1403 *xra, unsigned int addr,
drivers/gpio/gpio-xra1403.c line 57
Quoted 10 lines
drivers/gpio/gpio-xra1403.c new file +10
-0+ unsigned int bit) +{ +int ret; + + ret =xra1403_get_byte (xra, addr + (bit >7 )); +if (ret <0 ) +return ret; + +return !!(ret &BIT (bit %8 )); +}
This looks like it can use regmap-spi right off, do you agree?
git grep devm_regmap_init_spi
should give you some examples of how to use it.
If it's not off-the shelf regmap drivers like drivers/iio/pressure/mpl115_spi.c
give examples of how to make more elaborate custom SPI transfers with regmap.
Quoted 24 lines
drivers/gpio/gpio-xra1403.c new file +24
-0+static int xra1403_set_bit (struct xra1403 *xra,unsigned int addr, +unsigned int bit,int value) +{ +int ret; +u8 mask; +u8 tx[2 ]; + + addr += bit >7 ; + +mutex_lock (&xra->lock); + + ret =xra1403_get_byte (xra, addr); +if (ret <0 ) + goto out_unlock; + + mask =BIT (bit %8 ); +if (value) + value = ret | mask; +else + value = ret & ~mask; + +if (value != ret) { + tx[0 ] = addr <<1 ; + tx[1 ] = value;
drivers/gpio/gpio-xra1403.c line 92
Quoted 10 lines
drivers/gpio/gpio-xra1403.c new file +10
-0+ ret =spi_write (xra->spi, tx,sizeof (tx)); + }else { + ret =0 ; + } + +out_unlock: +mutex_unlock (&xra->lock); + +return ret; +}
Classical mask-and-set implementation right?
With regmap this becomes simply regmap_update_bits(map, addr, mask, set)
Quoted 5 lines
drivers/gpio/gpio-xra1403.c new file +5
-0+static int xra1403_probe (struct spi_device *spi) +{ +struct xra1403 *xra; +struct gpio_desc *reset_gpio; +
drivers/gpio/gpio-xra1403.c line 177
Quoted 10 lines
drivers/gpio/gpio-xra1403.c new file +10
-0+ xra =devm_kzalloc (&spi->dev,sizeof (*xra),GFP_KERNEL ); +if (!xra) +return -ENOMEM ; + +/* bring the chip out of reset */ + reset_gpio =gpiod_get_optional (&spi->dev,"reset" ,GPIOD_OUT_LOW ); +if (IS_ERR (reset_gpio)) +dev_warn (&spi->dev,"could not get reset-gpios\n" ); +else if (reset_gpio) +gpiod_put (reset_gpio);
I don't think you should put it, other than in the remove() function and in that case you need to have it in the state container.
drivers/gpio/gpio-xra1403.c line 182
Quoted 4 lines
drivers/gpio/gpio-xra1403.c new file +4
-0+mutex_init (&xra->lock); + + xra->chip.direction_input = xra1403_direction_input; + xra->chip.direction_output = xra1403_direction_output;
Please implement .get_direction(). This is very nice to have.
drivers/gpio/gpio-xra1403.c line 205
Quoted 5 lines
drivers/gpio/gpio-xra1403.c new file +5
-0+static int xra1403_remove (struct spi_device *spi) +{ +struct xra1403 *xra =spi_get_drvdata (spi); + +gpiochip_remove (&xra->chip);
Use devm_gpiochip_add_data() and this remove is not needed at all.
Quoted 6 lines
drivers/gpio/gpio-xra1403.c new file +6
-0+static int __init xra1403_init (void ) +{ +return spi_register_driver (&xra1403_driver); +} + +/*
drivers/gpio/gpio-xra1403.c line 247
Quoted 10 lines
drivers/gpio/gpio-xra1403.c new file +10
-0+* register after spi postcore initcall and before +* subsys initcalls that may rely on these GPIOs +*/ +subsys_initcall (xra1403_init); + +static void __exit xra1403_exit(void) +{ +spi_unregister_driver (&xra1403_driver); +} +module_exit (xra1403_exit);
This seems like tricksy. Just module_spi_driver()
should be fine don't you think?
Yours,
Linus Walleij
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PATCH 1/3 gpio - Add EXAR XRA1403 SPI GPIO expander driver
Quoted 21 lines
-----Original Message-----
From: Linus Walleij [mailto:[email protected]]
Sent: 29 March 2017 05:07
To: Han, Nandor (GE Healthcare) <[email protected]>
Cc: Alexandre Courbot <[email protected]>; Rob Herring <[email protected]>; Mark Rutland <[email protected]>; [email protected]; [email protected]; [email protected]; Malinen, Semi (GE Healthcare) <[email protected]>
Subject: EXT: Re: [PATCH 1/3] gpio - Add EXAR XRA1403 SPI GPIO expander driverQuoted 2 lines · Nandor Han
This is a simple driver that provides a
/sys/class/gpiointerface for controlling and configuring the GPIO lines.Use the gpio tools in
tools/gpio, use the characcter device. Do not use sysfs. Change this to reference the tools.Quoted 2 lines
It does not provide support for chip select or interrupts.
Quoted 8 lines
Quoted 2 lines
Signed-off-by Nandor Han <[email protected]>Signed-off-by Semi Malinen <[email protected]>(...)
Quoted 1 line
+exar Exar Corporation
Send this as a separate patch to the DT bindings maintainer (Rob Herring.)
OK. I will create a separate patch with this one.
I guess is not an issue to send all the patches to Rob as well.
<snip>
Quoted 10 lines
drivers/gpio/gpio-xra1403.c line 57
Quoted 7 lines
drivers/gpio/gpio-xra1403.c new file +7
-0+ + ret =xra1403_get_byte (xra, addr + (bit >7 )); +if (ret <0 ) +return ret; + +return !!(ret &BIT (bit %8 )); +}This looks like it can use regmap-spi right off, do you agree?
Yes. Using regmap-spi will definitely improve the code readability and reduce boilerplate. Done.
Quoted 8 lines
git grep
devm_regmap_init_spi
should give you some examples of how to use it.If it's not off-the shelf regmap drivers like
drivers/iio/pressure/mpl115_spi.c
give examples of how to make more elaborate custom SPI transfers with regmap.
Thanks, I did check other drivers as examples.
Not that I needed for this driver, but ...mpl115_spi.c doesn't seem to use regmap (checked on next-20170327)
<snip>
Quoted 9 lines
Quoted 9 lines
drivers/gpio/gpio-xra1403.c new file +9
-0+ +if (value != ret) { + tx[0 ] = addr <<1 ; + tx[1 ] = value; + ret =spi_write (xra->spi, tx,sizeof (tx)); + }else { + ret =0 ; + } +
Quoted 9 lines
drivers/gpio/gpio-xra1403.c line 92
Quoted 5 lines
drivers/gpio/gpio-xra1403.c new file +5
-0+out_unlock: +mutex_unlock (&xra->lock); + +return ret; +}Classical mask-and-set implementation right?
With regmap this becomes simplyregmap_update_bits(map, addr, mask, set)
True. :)
<snip>
Quoted 10 lines
drivers/gpio/gpio-xra1403.c line 177
Quoted 6 lines
drivers/gpio/gpio-xra1403.c new file +6
-0+/* bring the chip out of reset */ + reset_gpio =gpiod_get_optional (&spi->dev,"reset" ,GPIOD_OUT_LOW ); +if (IS_ERR (reset_gpio)) +dev_warn (&spi->dev,"could not get reset-gpios\n" ); +else if (reset_gpio) +gpiod_put (reset_gpio);I don't think you should put it, other than in the
remove()function and in that case you need to have it in the state container.
Can you please be more explicit here.
Currently I'm trying to bring the device out from reset in case reset GPIO is provided. I don't see how this could be done in remove() :)
Quoted 8 lines
drivers/gpio/gpio-xra1403.c line 182
Quoted 5 lines
drivers/gpio/gpio-xra1403.c new file +4
-0+mutex_init (&xra->lock); + + xra->chip.direction_input = xra1403_direction_input; + xra->chip.direction_output = xra1403_direction_output;Please implement .get_direction(). This is very nice to have.
Done
Quoted 9 lines
drivers/gpio/gpio-xra1403.c line 205
Quoted 5 lines
drivers/gpio/gpio-xra1403.c new file +5
-0+static int xra1403_remove (struct spi_device *spi) +{ +struct xra1403 *xra =spi_get_drvdata (spi); + +gpiochip_remove (&xra->chip);Use
devm_gpiochip_add_data()and this remove is not needed at all.
True. Done
<snip>
Quoted 10 lines
drivers/gpio/gpio-xra1403.c line 247
Quoted 7 lines
drivers/gpio/gpio-xra1403.c new file +7
-0+subsys_initcall (xra1403_init); + +static void __exit xra1403_exit(void) +{ +spi_unregister_driver (&xra1403_driver); +} +module_exit (xra1403_exit);This seems like tricksy. Just
module_spi_driver()should be fine don't you think?
Yeah. TBH I don't have a strong reason why module_spi_driver init level shouldn't be enough. Done.
Regards,
Nandor
Re: [PATCH 1/3] gpio - Add EXAR XRA1403 SPI GPIO expander driver
Quoted 8 lines · Nandor (GE Healthcare)
[Me]
Quoted 7 lines
Quoted 6 lines
drivers/gpio/gpio-xra1403.c new file +6
-0+/* bring the chip out of reset */ + reset_gpio =gpiod_get_optional (&spi->dev,"reset" ,GPIOD_OUT_LOW ); +if (IS_ERR (reset_gpio)) +dev_warn (&spi->dev,"could not get reset-gpios\n" ); +else if (reset_gpio) +gpiod_put (reset_gpio);
Quoted 8 lines
Quoted 3 lines
I don't think you should put it, other than in the
remove()function and in that case you need to have it in the state container.Can you please be more explicit here.
Currently I'm trying to bring the device out from reset in case reset GPIO is provided. I don't see how this could be done in
remove():)
If you issue gpiod_put() you release the GPIO hande so something else can go in and grab the GPIO and assert the reset.
This is not what you want to make possible: you want to hold this gpiod handle as long as the driver is running. devm_gpiod_get_optional() will do the trick if you don't want to put the handle under explicit control.
Yours,
Linus Walleij
PATCH 1/3 gpio - Add EXAR XRA1403 SPI GPIO expander driver
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Rob Herring
maintainerRe: [PATCH 1/3] gpio - Add EXAR XRA1403 SPI GPIO expander driver
In reply to Nandor HanQuoted 8 lines · Nandor Han
This is a simple driver that provides a
/sys/class/gpiointerface for controlling and configuring the GPIO lines. It does not provide support for chip select or interrupts.Signed-off-by Nandor Han <[email protected]>Signed-off-by Semi Malinen <[email protected]>--- .../devicetree/bindings/vendor-prefixes.txt | 1 +
This should go with the binding patch or by itself.
Quoted 5 lines
drivers/gpio/Kconfig | 5 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-xra1403.c | 252 +++++++++++++++++++++ 4 files changed, 259 insertions(+) create mode 100644 drivers/gpio/gpio-xra1403.c
PATCH 2/3 doc,dts - add XRA1403 DTS binding documentation
In reply to Nandor HanAdd the XRA1403 DTS binding documentation.
--- .../devicetree/bindings/gpio/gpio-xra1403.txt | 37 ++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/gpio-xra1403.txt
Documentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +37 -0
@@ -0,0 +1,37 @@ +GPIO Driver for XRA1403 16-BIT GPIO Expander With Reset Input from EXAR + +The XRA1403 is an 16-bit GPIO expander with an SPI interface. Features available: + - Individually programmable inputs: + - Internal pull-up resistors + - Polarity inversion + - Individual interrupt enable + - Rising edge and/or Falling edge interrupt + - Input filter + - Individually programmable outputs + - Output Level Control + - Output Three-State Control + +Properties +---------- +Check documentation for SPI and GPIO controllers regarding properties needed to configure the node. + + - compatible = "exar,xra1403". + - reg = SPI id of the device. + - gpio-controller: mark the node as gpio. + +Optional properties: +------------------- + - reset-gpios: in case available used to control the device reset line. + +Example +-------- + + gpioxra0: gpio@2 { + compatible = "exar,xra1403"; + reg = <2>; + gpio-controller; + #gpio-cells = <2>; + reset-gpios = <&gpio3 6 GPIO_ACTIVE_LOW>; + spi-max-frequency = <1000000>; + status = "okay"; + };
Signature · 1 line
2.10.1
Re: [PATCH 2/3] doc,dts - add XRA1403 DTS binding documentation
Quoted 3 lines · Nandor Han
Add the XRA1403 DTS binding documentation.
Signed-off-by Nandor Han <[email protected]>
There is no big problem with this but:
Documentation/devicetree/bindings/gpio/gpio-xra1403.txt line 9
Quoted 7 lines
Documentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +7
-0+The XRA1403 is an 16-bit GPIO expander with an SPI interface. Features available: + - Individually programmable inputs: + - Internal pull-up resistors + - Polarity inversion + - Individual interrupt enable + - Rising edge and/or Falling edge interrupt + - Input filter
Since you mention that it has interrupts maybe you want to add bindings for the cascaded interrupt and the interrupt-controller; keyword etc already now.
We just document what the hardware can do, we don't have to do all of it in the first Linux driver submission.
Yours,
Linus Walleij
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Rob Herring
maintainerRe: [PATCH 2/3] doc,dts - add XRA1403 DTS binding documentation
In reply to Nandor HanQuoted 1 line · Nandor Han
Add the XRA1403 DTS binding documentation.
"dt-bindings: gpio: ..." for the subject prefix please.
Quoted 23 lines
Signed-off-by Nandor Han <[email protected]>--- .../devicetree/bindings/gpio/gpio-xra1403.txt | 37 ++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/gpio-xra1403.txtDocumentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +10
-0@@ -0,0 +1,37 @@ +GPIO Driver for XRA1403 16-BIT GPIO Expander With Reset Input from EXAR + +The XRA1403 is an 16-bit GPIO expander with an SPI interface. Features available: + - Individually programmable inputs: + - Internal pull-up resistors + - Polarity inversion + - Individual interrupt enable + - Rising edge and/or Falling edge interrupt + - Input filter + - Individually programmable outputs
Documentation/devicetree/bindings/gpio/gpio-xra1403.txt line 20
Quoted 10 lines
Documentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +10
-0+ - Output Level Control + - Output Three-State Control + +Properties +---------- +Check documentation for SPI and GPIO controllers regarding properties needed to configure the node. + + - compatible = "exar,xra1403". + - reg = SPI id of the device. + - gpio-controller: mark the node as gpio.
#gpio-cells?
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Documentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +6
-0+ +Optional properties: +------------------- + - reset-gpios: in case available used to control the device reset line. + +Example
Documentation/devicetree/bindings/gpio/gpio-xra1403.txt line 36
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Documentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +10
-0+-------- + + gpioxra0: gpio@2 { + compatible = "exar,xra1403"; + reg = <2>; + gpio-controller; + #gpio-cells = <2>; + reset-gpios = <&gpio3 6 GPIO_ACTIVE_LOW>; + spi-max-frequency = <1000000>; + status = "okay";
Don't show status in examples.
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Documentation/devicetree/bindings/gpio/gpio-xra1403.txt new file +1
-0+ };Signature · 1 line
2.10.1
PATCH 3/3 Add XRA1403 support to MAINTAINERS file
In reply to Nandor HanAdd the XRA1403 support to MAINTAINERS list.
--- MAINTAINERS | 8 ++++++++ 1 file changed, 8 insertions(+)
MAINTAINERS +8 -0
@@ -13903,6 +13903,14 @@ L: [email protected] S: Supported F: drivers/char/xillybus/ +XRA1403 GPIO EXPANDER +M: Nandor Han <[email protected]> +M: Semi Malinen <[email protected]> +L: [email protected] +S: Maintained +F: drivers/gpio/gpio-xra1403.c +F: Documentation/devicetree/bindings/gpio/gpio-xra1403.txt + XTENSA XTFPGA PLATFORM SUPPORT M: Max Filippov <[email protected]> L: [email protected]
Signature · 1 line
2.10.1
Quoted 10 lines · Nandor Han
Testing:
1. XRA1403 connected to iMX53 MCU
2. Export gpio from userspace
3. Verify that corresponding gpio directories are created in/sys/class/gpio/gpioXX
4. Export gpios from first and second bank as output
5. Set the output gpio pin to high/low and verify with the oscilloscope that gpio status is according with the configured value.
Do *NOT* use the sysfs for testing GPIO.
This is being phased out.
Use the tools in tools/gpio/* so that you exercise the character device instead of the old deprecated ABI.
Yours,
Linus Walleij
cover XRA1403,gpio - add XRA1403 gpio expander driver
Quoted 10 lines
-----Original Message-----
From: Linus Walleij [mailto:[email protected]]
Sent: 29 March 2017 04:51
To: Han, Nandor (GE Healthcare) <[email protected]>
Cc: Alexandre Courbot <[email protected]>; Rob Herring <[email protected]>; Mark Rutland <[email protected]>; [email protected]; [email protected]; [email protected]
Subject: EXT: Re: [PATCH 0/3] XRA1403,gpio - add XRA1403 gpio expander driver
<snip>
Quoted 6 lines
Do *NOT* use the sysfs for testing GPIO.
This is being phased out.Use the tools in
tools/gpio/*so that you exercise the character device instead of the old deprecated ABI.
Thanks Linus, really good and helpful comments. I agree that make more sense to test with tools/gpio/*.
Quoted 2 lines
Yours,
Linus Walleij