1 files changed, 207 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-spear-spics.c b/drivers/gpio/gpio-spear-spics.c
new file mode 100644
index 000000000..69ffca5b0
--- /dev/null
+++ b/drivers/gpio/gpio-spear-spics.c
@@ -0,0 +1,207 @@
+/*
+ * SPEAr platform SPI chipselect abstraction over gpiolib
+ *
+ * Copyright (C) 2012 ST Microelectronics
+ * Shiraz Hashim <shiraz.linux.kernel@gmail.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;
+
+	spics = devm_kzalloc(&pdev->dev, sizeof(*spics), GFP_KERNEL);
+	if (!spics)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spics->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spics->base))
+		return PTR_ERR(spics->base);
+
+	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 = {
+		.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.linux.kernel@gmail.com>");
+MODULE_DESCRIPTION("STMicroelectronics SPEAr SPI Chip Select Abstraction");
+MODULE_LICENSE("GPL");