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935c500c37
The XWAY family allows to extend the number of gpios by using shift registers or latches. This patch adds the 2 drivers needed for this. The extended gpios are output only. [ralf@linux-mips.org: Fixed ltq_stp_probe section() attributes.] Signed-off-by: John Crispin <blogic@openwrt.org> Signed-off-by: Ralph Hempel <ralph.hempel@lantiq.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/2258/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
127 lines
3.1 KiB
C
127 lines
3.1 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*
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* Copyright (C) 2010 John Crispin <blogic@openwrt.org>
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/platform_device.h>
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#include <linux/mutex.h>
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#include <linux/gpio.h>
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#include <linux/io.h>
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#include <lantiq_soc.h>
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/*
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* By attaching hardware latches to the EBU it is possible to create output
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* only gpios. This driver configures a special memory address, which when
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* written to outputs 16 bit to the latches.
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*/
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#define LTQ_EBU_BUSCON 0x1e7ff /* 16 bit access, slowest timing */
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#define LTQ_EBU_WP 0x80000000 /* write protect bit */
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/* we keep a shadow value of the last value written to the ebu */
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static int ltq_ebu_gpio_shadow = 0x0;
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static void __iomem *ltq_ebu_gpio_membase;
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static void ltq_ebu_apply(void)
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{
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unsigned long flags;
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spin_lock_irqsave(&ebu_lock, flags);
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ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
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*((__u16 *)ltq_ebu_gpio_membase) = ltq_ebu_gpio_shadow;
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ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
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spin_unlock_irqrestore(&ebu_lock, flags);
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}
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static void ltq_ebu_set(struct gpio_chip *chip, unsigned offset, int value)
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{
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if (value)
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ltq_ebu_gpio_shadow |= (1 << offset);
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else
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ltq_ebu_gpio_shadow &= ~(1 << offset);
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ltq_ebu_apply();
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}
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static int ltq_ebu_direction_output(struct gpio_chip *chip, unsigned offset,
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int value)
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{
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ltq_ebu_set(chip, offset, value);
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return 0;
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}
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static struct gpio_chip ltq_ebu_chip = {
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.label = "ltq_ebu",
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.direction_output = ltq_ebu_direction_output,
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.set = ltq_ebu_set,
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.base = 72,
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.ngpio = 16,
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.can_sleep = 1,
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.owner = THIS_MODULE,
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};
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static int ltq_ebu_probe(struct platform_device *pdev)
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{
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int ret = 0;
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struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!res) {
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dev_err(&pdev->dev, "failed to get memory resource\n");
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return -ENOENT;
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}
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res = devm_request_mem_region(&pdev->dev, res->start,
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resource_size(res), dev_name(&pdev->dev));
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if (!res) {
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dev_err(&pdev->dev, "failed to request memory resource\n");
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return -EBUSY;
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}
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ltq_ebu_gpio_membase = devm_ioremap_nocache(&pdev->dev, res->start,
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resource_size(res));
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if (!ltq_ebu_gpio_membase) {
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dev_err(&pdev->dev, "Failed to ioremap mem region\n");
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return -ENOMEM;
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}
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/* grab the default shadow value passed form the platform code */
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ltq_ebu_gpio_shadow = (unsigned int) pdev->dev.platform_data;
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/* tell the ebu controller which memory address we will be using */
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ltq_ebu_w32(pdev->resource->start | 0x1, LTQ_EBU_ADDRSEL1);
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/* write protect the region */
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ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
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ret = gpiochip_add(<q_ebu_chip);
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if (!ret)
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ltq_ebu_apply();
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return ret;
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}
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static struct platform_driver ltq_ebu_driver = {
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.probe = ltq_ebu_probe,
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.driver = {
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.name = "ltq_ebu",
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.owner = THIS_MODULE,
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},
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};
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static int __init ltq_ebu_init(void)
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{
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int ret = platform_driver_register(<q_ebu_driver);
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if (ret)
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pr_info("ltq_ebu : Error registering platfom driver!");
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return ret;
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}
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postcore_initcall(ltq_ebu_init);
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