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");