[PATCH v3] gpio: Add driver for basic memory-mapped GPIOcontrollers
From: Anton Vorontsov
Date: Fri Aug 27 2010 - 11:58:02 EST
The basic GPIO controllers may be found in various on-board FPGA
and ASIC solutions that are used to control board's switches, LEDs,
chip-selects, Ethernet/USB PHY power, etc.
Usually these controllers do not privide any means of pin setup
(in/out/open drain).
The driver provides:
- Support for 8/16/32/64 bits registers;
- Support for GPIO controllers with clear/set registers;
- Support for GPIO controllers with a single "data" register;
- Support for big endian bits/GPIOs ordering (mostly used on PowerPC).
Signed-off-by: Anton Vorontsov <cbouatmailru@xxxxxxxxx>
---
On Thu, Aug 26, 2010 at 03:48:31PM -0700, David Brownell wrote:
[...]
> > Just kiding, of course. basic_mmio.c works for me.
>
> OK, how about resubmitting? With that name?
Sure thing.
> Be sure to add a bit of documentation about
> the controller requirements ... basically that
> it has a register from which all values can be
> read, and that either that register can be written,
> or there's a pair of set-bit/clear-bit registers
> affecting that register and the output pins.
>
> Might be worth mentioning how trivial it is to do
> that in hardware like CPLDs/FPGAS/etc, which is
> why this handles different word sizes/endianness.
> and the expectation that in at least some cases
> this will be used with roll-your-own ASIC/FPGA
> logic in Verilog or VHDL (yes?).
Yep. Done.
> > I also think it makes sense to drop gpio_ prefix,
> > as the driver is already in gpio/ directory.
>
> No, keep it; files move around sometimes, and it's
> best if that loses no information.
OK.
Also addressed Mark's comments wrt getting resources
by name. Plus, it appears that there's also gc.dev field
in gpio_chip, fill it too.
I hope it's perfect now. :-)
Thanks!
drivers/gpio/Kconfig | 5 +
drivers/gpio/Makefile | 1 +
drivers/gpio/basic_mmio_gpio.c | 278 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 284 insertions(+), 0 deletions(-)
create mode 100644 drivers/gpio/basic_mmio_gpio.c
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index f623953..d1d1c24 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -70,6 +70,11 @@ config GPIO_MAX730X
comment "Memory mapped GPIO expanders:"
+config GPIO_BASIC_MMIO
+ tristate "Basic memory-mapped GPIO controllers support"
+ help
+ Say yes here to support basic memory-mapped GPIO controllers.
+
config GPIO_IT8761E
tristate "IT8761E GPIO support"
depends on GPIOLIB
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index a69e060..dfb571b 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_GPIOLIB) += gpiolib.o
obj-$(CONFIG_GPIO_ADP5520) += adp5520-gpio.o
obj-$(CONFIG_GPIO_ADP5588) += adp5588-gpio.o
+obj-$(CONFIG_GPIO_BASIC_MMIO) += basic_mmio_gpio.o
obj-$(CONFIG_GPIO_LANGWELL) += langwell_gpio.o
obj-$(CONFIG_GPIO_MAX730X) += max730x.o
obj-$(CONFIG_GPIO_MAX7300) += max7300.o
diff --git a/drivers/gpio/basic_mmio_gpio.c b/drivers/gpio/basic_mmio_gpio.c
new file mode 100644
index 0000000..6526959
--- /dev/null
+++ b/drivers/gpio/basic_mmio_gpio.c
@@ -0,0 +1,278 @@
+/*
+ * Driver for basic memory-mapped GPIO controllers.
+ *
+ * Copyright 2008 MontaVista Software, Inc.
+ * Copyright 2008,2010 Anton Vorontsov <cbouatmailru@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * ....``.```~~~~````.`.`.`.`.```````'',,,.........`````......`.......
+ * ...`` ```````..
+ * ..The simplest form of a GPIO controller that the driver supports is``
+ * `.just a single "data" register, where GPIO state can be read and/or `
+ * ..written. ,,..``~~~~ .....``.`.`.~~.```.`.........``````.```````
+ * ```````
+ * __/~~|___/~| . ```~~~~~~ ,~.`.`.`.`````.~~...,,,,...
+ * |___________|~$@~~~ %~~ .. Implementing such a GPIO .
+ * o ` . ` controller in FPGA is,`.
+ * `....trivial. '~`.```.````
+ * ```````
+ * .```````~~~~`..`.``.``.
+ * . The driver supports `... ,..```.`~~~```````````````....````.``,,.
+ * . big-endian notation, just`. ... A bit more sophisticated controllers ,
+ * . register the device with -be`. . with a pair of set/clear-bit registers ,
+ * `.. suffix. ```~~`````....`.` . affecting the data register and the .`
+ * ``.`.``...``` ```.. output pins are also supported.`
+ * ^^ `````.`````````.,``~``~``~~``````
+ * . ^^
+ * ,..`.`.`...````````````......`.`.`.`.`.`..`.`.`..
+ * .. The expectation is that in at least some cases . ,-~~~-,
+ * .this will be used with roll-your-own ASIC/FPGA .` \ /
+ * .logic in Verilog or VHDL. ~~~`````````..`````~~` \ /
+ * ..````````......``````````` \o_
+ * |
+ * ^^ / \
+ *
+ * ...`````~~`.....``.`..........``````.`.``.```........``.
+ * ` 8, 16, 32 and 64 bits registers are supported, and``.
+ * . the number of GPIOs is determined by the width of ~
+ * .. the registers. ,............```.`.`..`.`.~~~.`.`.`~
+ * `.......````.```
+ */
+
+#include <linux/init.h>
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include <linux/log2.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/mod_devicetable.h>
+
+struct bgpio_chip {
+ struct gpio_chip gc;
+ void __iomem *reg_dat;
+ void __iomem *reg_set;
+ void __iomem *reg_clr;
+ spinlock_t lock;
+
+ int bits;
+ int big_endian_bits;
+
+ /* shadowed data register to clear/set bits safely */
+ unsigned long data;
+};
+
+static struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
+{
+ return container_of(gc, struct bgpio_chip, gc);
+}
+
+static unsigned long bgpio_in(struct bgpio_chip *bgc)
+{
+ switch (bgc->bits) {
+ case 8:
+ return __raw_readb(bgc->reg_dat);
+ case 16:
+ return __raw_readw(bgc->reg_dat);
+ case 32:
+ return __raw_readl(bgc->reg_dat);
+#if BITS_PER_LONG >= 64
+ case 64:
+ return __raw_readq(bgc->reg_dat);
+#endif
+ }
+ BUG();
+}
+
+static void bgpio_out(struct bgpio_chip *bgc, void __iomem *reg,
+ unsigned long data)
+{
+ switch (bgc->bits) {
+ case 8:
+ __raw_writeb(data, reg);
+ return;
+ case 16:
+ __raw_writew(data, reg);
+ return;
+ case 32:
+ __raw_writel(data, reg);
+ return;
+#if BITS_PER_LONG >= 64
+ case 64:
+ __raw_writeq(data, reg);
+ return;
+#endif
+ }
+ BUG();
+}
+
+static unsigned long bgpio_pin2mask(struct bgpio_chip *bgc, unsigned int pin)
+{
+ if (bgc->big_endian_bits)
+ return 1 << (bgc->bits - 1 - pin);
+ else
+ return 1 << pin;
+}
+
+static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+ struct bgpio_chip *bgc = to_bgpio_chip(gc);
+
+ return bgpio_in(bgc) & bgpio_pin2mask(bgc, gpio);
+}
+
+static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+ struct bgpio_chip *bgc = to_bgpio_chip(gc);
+ unsigned long mask = bgpio_pin2mask(bgc, gpio);
+ unsigned long flags;
+
+ if (bgc->reg_set) {
+ if (val)
+ bgpio_out(bgc, bgc->reg_set, mask);
+ else
+ bgpio_out(bgc, bgc->reg_clr, mask);
+ return;
+ }
+
+ spin_lock_irqsave(&bgc->lock, flags);
+
+ if (val)
+ bgc->data |= mask;
+ else
+ bgc->data &= ~mask;
+
+ bgpio_out(bgc, bgc->reg_dat, bgc->data);
+
+ spin_unlock_irqrestore(&bgc->lock, flags);
+}
+
+static int bgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
+{
+ return 0;
+}
+
+static int bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+ bgpio_set(gc, gpio, val);
+ return 0;
+}
+
+static int __devinit bgpio_probe(struct platform_device *pdev)
+{
+ const struct platform_device_id *platid = platform_get_device_id(pdev);
+ struct device *dev = &pdev->dev;
+ struct bgpio_chip *bgc;
+ struct resource *res_dat;
+ struct resource *res_set;
+ struct resource *res_clr;
+ resource_size_t dat_sz;
+ int bits;
+
+ res_dat = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
+ if (!res_dat)
+ return -EINVAL;
+
+ dat_sz = resource_size(res_dat);
+ if (!is_power_of_2(dat_sz))
+ return -EINVAL;
+
+ bits = dat_sz * 8;
+ if (bits > BITS_PER_LONG)
+ return -EINVAL;
+
+ bgc = devm_kzalloc(dev, sizeof(*bgc), GFP_KERNEL);
+ if (!bgc)
+ return -ENOMEM;
+
+ bgc->reg_dat = devm_ioremap(dev, res_dat->start, dat_sz);
+ if (!bgc->reg_dat)
+ return -ENOMEM;
+
+ res_set = platform_get_resource_byname(pdev, IORESOURCE_MEM, "set");
+ res_clr = platform_get_resource_byname(pdev, IORESOURCE_MEM, "clr");
+ if (res_set && res_clr) {
+ if (resource_size(res_set) != resource_size(res_clr) ||
+ resource_size(res_set) != dat_sz)
+ return -EINVAL;
+
+ bgc->reg_set = devm_ioremap(dev, res_set->start, dat_sz);
+ bgc->reg_clr = devm_ioremap(dev, res_clr->start, dat_sz);
+ if (!bgc->reg_set || !bgc->reg_clr)
+ return -ENOMEM;
+ } else if (res_set || res_clr) {
+ return -EINVAL;
+ }
+
+ spin_lock_init(&bgc->lock);
+
+ bgc->bits = bits;
+ bgc->big_endian_bits = !strcmp(platid->name, "basic-mmio-gpio-be");
+ bgc->data = bgpio_in(bgc);
+
+ bgc->gc.ngpio = bits;
+ bgc->gc.direction_input = bgpio_dir_in;
+ bgc->gc.direction_output = bgpio_dir_out;
+ bgc->gc.get = bgpio_get;
+ bgc->gc.set = bgpio_set;
+ bgc->gc.dev = dev;
+ bgc->gc.label = dev_name(dev);
+
+ if (dev->platform_data)
+ bgc->gc.base = (unsigned long)dev->platform_data;
+ else
+ bgc->gc.base = -1;
+
+ dev_set_drvdata(dev, bgc);
+
+ return gpiochip_add(&bgc->gc);
+}
+
+static int __devexit bgpio_remove(struct platform_device *pdev)
+{
+ struct bgpio_chip *bgc = dev_get_drvdata(&pdev->dev);
+
+ return gpiochip_remove(&bgc->gc);
+}
+
+static const struct platform_device_id bgpio_id_table[] = {
+ { "basic-mmio-gpio", },
+ { "basic-mmio-gpio-be", },
+ {},
+};
+MODULE_DEVICE_TABLE(platform, bgpio_id_table);
+
+static struct platform_driver bgpio_driver = {
+ .driver = {
+ .name = "basic-mmio-gpio",
+ },
+ .id_table = bgpio_id_table,
+ .probe = bgpio_probe,
+ .remove = __devexit_p(bgpio_remove),
+};
+
+static int __init bgpio_init(void)
+{
+ return platform_driver_register(&bgpio_driver);
+}
+module_init(bgpio_init);
+
+static void __exit bgpio_exit(void)
+{
+ platform_driver_unregister(&bgpio_driver);
+}
+module_exit(bgpio_exit);
+
+MODULE_DESCRIPTION("Driver for basic memory-mapped GPIO controllers");
+MODULE_AUTHOR("Anton Vorontsov <cbouatmailru@xxxxxxxxx>");
+MODULE_LICENSE("GPL");
--
1.7.0.5
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