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- /*
- * 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/init.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 = gpiochip_get_data(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 = gpiochip_get_data(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 = gpiochip_get_data(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.parent = &pdev->dev;
- spics->chip.owner = THIS_MODULE;
- spics->last_off = -1;
- ret = devm_gpiochip_add_data(&pdev->dev, &spics->chip, spics);
- 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" },
- {}
- };
- 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);
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