diff options
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/spear_spics.txt | 50 | ||||
| -rw-r--r-- | arch/arm/plat-spear/Kconfig | 1 | ||||
| -rw-r--r-- | drivers/gpio/Kconfig | 7 | ||||
| -rw-r--r-- | drivers/gpio/Makefile | 1 | ||||
| -rw-r--r-- | drivers/gpio/gpio-spear-spics.c | 217 |
5 files changed, 276 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/gpio/spear_spics.txt b/Documentation/devicetree/bindings/gpio/spear_spics.txt new file mode 100644 index 000000000000..96c37eb15075 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/spear_spics.txt @@ -0,0 +1,50 @@ +=== ST Microelectronics SPEAr SPI CS Driver === + +SPEAr platform provides a provision to control chipselects of ARM PL022 Prime +Cell spi controller through its system registers, which otherwise remains under +PL022 control. If chipselect remain under PL022 control then they would be +released as soon as transfer is over and TxFIFO becomes empty. This is not +desired by some of the device protocols above spi which expect (multiple) +transfers without releasing their chipselects. + +Chipselects can be controlled by software by turning them as GPIOs. SPEAr +provides another interface through system registers through which software can +directly control each PL022 chipselect. Hence, it is natural for SPEAr to export +the control of this interface as gpio. + +Required properties: + + * compatible: should be defined as "st,spear-spics-gpio" + * reg: mentioning address range of spics controller + * st-spics,peripcfg-reg: peripheral configuration register offset + * st-spics,sw-enable-bit: bit offset to enable sw control + * st-spics,cs-value-bit: bit offset to drive chipselect low or high + * st-spics,cs-enable-mask: chip select number bit mask + * st-spics,cs-enable-shift: chip select number program offset + * gpio-controller: Marks the device node as gpio controller + * #gpio-cells: should be 1 and will mention chip select number + +All the above bit offsets are within peripcfg register. + +Example: +------- +spics: spics@e0700000{ + compatible = "st,spear-spics-gpio"; + reg = <0xe0700000 0x1000>; + st-spics,peripcfg-reg = <0x3b0>; + st-spics,sw-enable-bit = <12>; + st-spics,cs-value-bit = <11>; + st-spics,cs-enable-mask = <3>; + st-spics,cs-enable-shift = <8>; + gpio-controller; + #gpio-cells = <2>; +}; + + +spi0: spi@e0100000 { + status = "okay"; + num-cs = <3>; + cs-gpios = <&gpio1 7 0>, <&spics 0>, + <&spics 1>; + ... +} diff --git a/arch/arm/plat-spear/Kconfig b/arch/arm/plat-spear/Kconfig index f8db7b2deb36..87dbd81bdf51 100644 --- a/arch/arm/plat-spear/Kconfig +++ b/arch/arm/plat-spear/Kconfig @@ -12,6 +12,7 @@ config ARCH_SPEAR13XX bool "ST SPEAr13xx with Device Tree" select ARM_GIC select CPU_V7 + select GPIO_SPEAR_SPICS select HAVE_SMP select MIGHT_HAVE_CACHE_L2X0 select PINCTRL diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 9e3fb3438718..4f592c615990 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -196,6 +196,13 @@ config GPIO_PXA help Say yes here to support the PXA GPIO device +config GPIO_SPEAR_SPICS + bool "ST SPEAr13xx SPI Chip Select as GPIO support" + depends on PLAT_SPEAR + select GENERIC_IRQ_CHIP + help + Say yes here to support ST SPEAr SPI Chip Select as GPIO device + config GPIO_STA2X11 bool "STA2x11/ConneXt GPIO support" depends on MFD_STA2X11 diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index 1c1b63fcaeb3..a268d99f4e43 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -59,6 +59,7 @@ obj-$(CONFIG_PLAT_SAMSUNG) += gpio-samsung.o obj-$(CONFIG_ARCH_SA1100) += gpio-sa1100.o obj-$(CONFIG_GPIO_SCH) += gpio-sch.o obj-$(CONFIG_GPIO_SODAVILLE) += gpio-sodaville.o +obj-$(CONFIG_GPIO_SPEAR_SPICS) += gpio-spear-spics.o obj-$(CONFIG_GPIO_STA2X11) += gpio-sta2x11.o obj-$(CONFIG_GPIO_STMPE) += gpio-stmpe.o obj-$(CONFIG_GPIO_STP_XWAY) += gpio-stp-xway.o diff --git a/drivers/gpio/gpio-spear-spics.c b/drivers/gpio/gpio-spear-spics.c new file mode 100644 index 000000000000..5f45fc4ed5d1 --- /dev/null +++ b/drivers/gpio/gpio-spear-spics.c @@ -0,0 +1,217 @@ +/* + * SPEAr platform SPI chipselect abstraction over gpiolib + * + * Copyright (C) 2012 ST Microelectronics + * Shiraz Hashim <shiraz.hashim@st.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/err.h> +#include <linux/gpio.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/types.h> + +/* maximum chipselects */ +#define NUM_OF_GPIO 4 + +/* + * Provision is available on some SPEAr SoCs to control ARM PL022 spi cs + * through system registers. This register lies outside spi (pl022) + * address space into system registers. + * + * It provides control for spi chip select lines so that any chipselect + * (out of 4 possible chipselects in pl022) can be made low to select + * the particular slave. + */ + +/** + * struct spear_spics - represents spi chip select control + * @base: base address + * @perip_cfg: configuration register + * @sw_enable_bit: bit to enable s/w control over chipselects + * @cs_value_bit: bit to program high or low chipselect + * @cs_enable_mask: mask to select bits required to select chipselect + * @cs_enable_shift: bit pos of cs_enable_mask + * @use_count: use count of a spi controller cs lines + * @last_off: stores last offset caller of set_value() + * @chip: gpio_chip abstraction + */ +struct spear_spics { + void __iomem *base; + u32 perip_cfg; + u32 sw_enable_bit; + u32 cs_value_bit; + u32 cs_enable_mask; + u32 cs_enable_shift; + unsigned long use_count; + int last_off; + struct gpio_chip chip; +}; + +/* gpio framework specific routines */ +static int spics_get_value(struct gpio_chip *chip, unsigned offset) +{ + return -ENXIO; +} + +static void spics_set_value(struct gpio_chip *chip, unsigned offset, int value) +{ + struct spear_spics *spics = container_of(chip, struct spear_spics, + chip); + u32 tmp; + + /* select chip select from register */ + tmp = readl_relaxed(spics->base + spics->perip_cfg); + if (spics->last_off != offset) { + spics->last_off = offset; + tmp &= ~(spics->cs_enable_mask << spics->cs_enable_shift); + tmp |= offset << spics->cs_enable_shift; + } + + /* toggle chip select line */ + tmp &= ~(0x1 << spics->cs_value_bit); + tmp |= value << spics->cs_value_bit; + writel_relaxed(tmp, spics->base + spics->perip_cfg); +} + +static int spics_direction_input(struct gpio_chip *chip, unsigned offset) +{ + return -ENXIO; +} + +static int spics_direction_output(struct gpio_chip *chip, unsigned offset, + int value) +{ + spics_set_value(chip, offset, value); + return 0; +} + +static int spics_request(struct gpio_chip *chip, unsigned offset) +{ + struct spear_spics *spics = container_of(chip, struct spear_spics, + chip); + u32 tmp; + + if (!spics->use_count++) { + tmp = readl_relaxed(spics->base + spics->perip_cfg); + tmp |= 0x1 << spics->sw_enable_bit; + tmp |= 0x1 << spics->cs_value_bit; + writel_relaxed(tmp, spics->base + spics->perip_cfg); + } + + return 0; +} + +static void spics_free(struct gpio_chip *chip, unsigned offset) +{ + struct spear_spics *spics = container_of(chip, struct spear_spics, + chip); + u32 tmp; + + if (!--spics->use_count) { + tmp = readl_relaxed(spics->base + spics->perip_cfg); + tmp &= ~(0x1 << spics->sw_enable_bit); + writel_relaxed(tmp, spics->base + spics->perip_cfg); + } +} + +static int spics_gpio_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct spear_spics *spics; + struct resource *res; + int ret; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(&pdev->dev, "invalid IORESOURCE_MEM\n"); + return -EBUSY; + } + + spics = devm_kzalloc(&pdev->dev, sizeof(*spics), GFP_KERNEL); + if (!spics) { + dev_err(&pdev->dev, "memory allocation fail\n"); + return -ENOMEM; + } + + spics->base = devm_request_and_ioremap(&pdev->dev, res); + if (!spics->base) { + dev_err(&pdev->dev, "request and ioremap fail\n"); + return -ENOMEM; + } + + if (of_property_read_u32(np, "st-spics,peripcfg-reg", + &spics->perip_cfg)) + goto err_dt_data; + if (of_property_read_u32(np, "st-spics,sw-enable-bit", + &spics->sw_enable_bit)) + goto err_dt_data; + if (of_property_read_u32(np, "st-spics,cs-value-bit", + &spics->cs_value_bit)) + goto err_dt_data; + if (of_property_read_u32(np, "st-spics,cs-enable-mask", + &spics->cs_enable_mask)) + goto err_dt_data; + if (of_property_read_u32(np, "st-spics,cs-enable-shift", + &spics->cs_enable_shift)) + goto err_dt_data; + + platform_set_drvdata(pdev, spics); + + spics->chip.ngpio = NUM_OF_GPIO; + spics->chip.base = -1; + spics->chip.request = spics_request; + spics->chip.free = spics_free; + spics->chip.direction_input = spics_direction_input; + spics->chip.direction_output = spics_direction_output; + spics->chip.get = spics_get_value; + spics->chip.set = spics_set_value; + spics->chip.label = dev_name(&pdev->dev); + spics->chip.dev = &pdev->dev; + spics->chip.owner = THIS_MODULE; + spics->last_off = -1; + + ret = gpiochip_add(&spics->chip); + if (ret) { + dev_err(&pdev->dev, "unable to add gpio chip\n"); + return ret; + } + + dev_info(&pdev->dev, "spear spics registered\n"); + return 0; + +err_dt_data: + dev_err(&pdev->dev, "DT probe failed\n"); + return -EINVAL; +} + +static const struct of_device_id spics_gpio_of_match[] = { + { .compatible = "st,spear-spics-gpio" }, + {} +}; +MODULE_DEVICE_TABLE(of, spics_gpio_of_match); + +static struct platform_driver spics_gpio_driver = { + .probe = spics_gpio_probe, + .driver = { + .owner = THIS_MODULE, + .name = "spear-spics-gpio", + .of_match_table = spics_gpio_of_match, + }, +}; + +static int __init spics_gpio_init(void) +{ + return platform_driver_register(&spics_gpio_driver); +} +subsys_initcall(spics_gpio_init); + +MODULE_AUTHOR("Shiraz Hashim <shiraz.hashim@st.com>"); +MODULE_DESCRIPTION("ST Microlectronics SPEAr SPI Chip Select Abstraction"); +MODULE_LICENSE("GPL"); |