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From 0f05af4c96c0272bb431ace33dd284a891e4fe41 Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Tue, 23 Feb 2016 19:56:04 +0000
Subject: [PATCH] bcm2835-virtgpio: Virtual GPIO driver
Add a virtual GPIO driver that uses the firmware mailbox interface to
request that the VPU toggles LEDs.
---
drivers/gpio/Kconfig | 6 +
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-bcm-virt.c | 214 +++++++++++++++++++++++++++++++++++
3 files changed, 221 insertions(+)
create mode 100644 drivers/gpio/gpio-bcm-virt.c
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -151,6 +151,12 @@ config GPIO_BCM_KONA
help
Turn on GPIO support for Broadcom "Kona" chips.
+config GPIO_BCM_VIRT
+ bool "Broadcom Virt GPIO"
+ depends on OF_GPIO && RASPBERRYPI_FIRMWARE && (ARCH_BCM2835 || COMPILE_TEST)
+ help
+ Turn on virtual GPIO support for Broadcom BCM283X chips.
+
config GPIO_BRCMSTB
tristate "BRCMSTB GPIO support"
default y if (ARCH_BRCMSTB || BMIPS_GENERIC)
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_GPIO_ASPEED) += gpio-aspeed
obj-$(CONFIG_GPIO_RASPBERRYPI_EXP) += gpio-raspberrypi-exp.o
obj-$(CONFIG_GPIO_BCM_KONA) += gpio-bcm-kona.o
obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd9571mwv.o
+obj-$(CONFIG_GPIO_BCM_VIRT) += gpio-bcm-virt.o
obj-$(CONFIG_GPIO_BRCMSTB) += gpio-brcmstb.o
obj-$(CONFIG_GPIO_BT8XX) += gpio-bt8xx.o
obj-$(CONFIG_GPIO_CLPS711X) += gpio-clps711x.o
--- /dev/null
+++ b/drivers/gpio/gpio-bcm-virt.c
@@ -0,0 +1,214 @@
+/*
+ * brcmvirt GPIO driver
+ *
+ * Copyright (C) 2012,2013 Dom Cobley <popcornmix@gmail.com>
+ * Based on gpio-clps711x.c by Alexander Shiyan <shc_work@mail.ru>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define MODULE_NAME "brcmvirt-gpio"
+#define NUM_GPIO 2
+
+struct brcmvirt_gpio {
+ struct gpio_chip gc;
+ u32 __iomem *ts_base;
+ /* two packed 16-bit counts of enabled and disables
+ Allows host to detect a brief enable that was missed */
+ u32 enables_disables[NUM_GPIO];
+ dma_addr_t bus_addr;
+};
+
+static int brcmvirt_gpio_dir_in(struct gpio_chip *gc, unsigned off)
+{
+ struct brcmvirt_gpio *gpio;
+ gpio = container_of(gc, struct brcmvirt_gpio, gc);
+ return -EINVAL;
+}
+
+static int brcmvirt_gpio_dir_out(struct gpio_chip *gc, unsigned off, int val)
+{
+ struct brcmvirt_gpio *gpio;
+ gpio = container_of(gc, struct brcmvirt_gpio, gc);
+ return 0;
+}
+
+static int brcmvirt_gpio_get(struct gpio_chip *gc, unsigned off)
+{
+ struct brcmvirt_gpio *gpio;
+ unsigned v;
+ gpio = container_of(gc, struct brcmvirt_gpio, gc);
+ v = readl(gpio->ts_base + off);
+ return (v >> off) & 1;
+}
+
+static void brcmvirt_gpio_set(struct gpio_chip *gc, unsigned off, int val)
+{
+ struct brcmvirt_gpio *gpio;
+ u16 enables, disables;
+ s16 diff;
+ bool lit;
+ gpio = container_of(gc, struct brcmvirt_gpio, gc);
+ enables = gpio->enables_disables[off] >> 16;
+ disables = gpio->enables_disables[off] >> 0;
+ diff = (s16)(enables - disables);
+ lit = diff > 0;
+ if ((val && lit) || (!val && !lit))
+ return;
+ if (val)
+ enables++;
+ else
+ disables++;
+ diff = (s16)(enables - disables);
+ BUG_ON(diff != 0 && diff != 1);
+ gpio->enables_disables[off] = (enables << 16) | (disables << 0);
+ writel(gpio->enables_disables[off], gpio->ts_base + off);
+}
+
+static int brcmvirt_gpio_probe(struct platform_device *pdev)
+{
+ int err = 0;
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct device_node *fw_node;
+ struct rpi_firmware *fw;
+ struct brcmvirt_gpio *ucb;
+ u32 gpiovirtbuf;
+
+ fw_node = of_parse_phandle(np, "firmware", 0);
+ if (!fw_node) {
+ dev_err(dev, "Missing firmware node\n");
+ return -ENOENT;
+ }
+
+ fw = rpi_firmware_get(fw_node);
+ if (!fw)
+ return -EPROBE_DEFER;
+
+ ucb = devm_kzalloc(dev, sizeof *ucb, GFP_KERNEL);
+ if (!ucb) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ ucb->ts_base = dma_zalloc_coherent(dev, PAGE_SIZE, &ucb->bus_addr, GFP_KERNEL);
+ if (!ucb->ts_base) {
+ pr_err("[%s]: failed to dma_alloc_coherent(%ld)\n",
+ __func__, PAGE_SIZE);
+ err = -ENOMEM;
+ goto out;
+ }
+
+ gpiovirtbuf = (u32)ucb->bus_addr;
+ err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_GPIOVIRTBUF,
+ &gpiovirtbuf, sizeof(gpiovirtbuf));
+
+ if (err || gpiovirtbuf != 0) {
+ dev_warn(dev, "Failed to set gpiovirtbuf, trying to get err:%x\n", err);
+ dma_free_coherent(dev, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
+ ucb->ts_base = 0;
+ ucb->bus_addr = 0;
+ }
+
+ if (!ucb->ts_base) {
+ err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_GET_GPIOVIRTBUF,
+ &gpiovirtbuf, sizeof(gpiovirtbuf));
+
+ if (err) {
+ dev_err(dev, "Failed to get gpiovirtbuf\n");
+ goto out;
+ }
+
+ if (!gpiovirtbuf) {
+ dev_err(dev, "No virtgpio buffer\n");
+ err = -ENOENT;
+ goto out;
+ }
+
+ // mmap the physical memory
+ gpiovirtbuf &= ~0xc0000000;
+ ucb->ts_base = ioremap(gpiovirtbuf, 4096);
+ if (ucb->ts_base == NULL) {
+ dev_err(dev, "Failed to map physical address\n");
+ err = -ENOENT;
+ goto out;
+ }
+ ucb->bus_addr = 0;
+ }
+ ucb->gc.label = MODULE_NAME;
+ ucb->gc.owner = THIS_MODULE;
+ //ucb->gc.dev = dev;
+ ucb->gc.of_node = np;
+ ucb->gc.base = 100;
+ ucb->gc.ngpio = NUM_GPIO;
+
+ ucb->gc.direction_input = brcmvirt_gpio_dir_in;
+ ucb->gc.direction_output = brcmvirt_gpio_dir_out;
+ ucb->gc.get = brcmvirt_gpio_get;
+ ucb->gc.set = brcmvirt_gpio_set;
+ ucb->gc.can_sleep = true;
+
+ err = gpiochip_add(&ucb->gc);
+ if (err)
+ goto out;
+
+ platform_set_drvdata(pdev, ucb);
+
+ return 0;
+out:
+ if (ucb->bus_addr) {
+ dma_free_coherent(dev, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
+ ucb->bus_addr = 0;
+ ucb->ts_base = NULL;
+ } else if (ucb->ts_base) {
+ iounmap(ucb->ts_base);
+ ucb->ts_base = NULL;
+ }
+ return err;
+}
+
+static int brcmvirt_gpio_remove(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ int err = 0;
+ struct brcmvirt_gpio *ucb = platform_get_drvdata(pdev);
+
+ gpiochip_remove(&ucb->gc);
+ if (ucb->bus_addr)
+ dma_free_coherent(dev, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
+ else if (ucb->ts_base)
+ iounmap(ucb->ts_base);
+ return err;
+}
+
+static const struct of_device_id __maybe_unused brcmvirt_gpio_ids[] = {
+ { .compatible = "brcm,bcm2835-virtgpio" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, brcmvirt_gpio_ids);
+
+static struct platform_driver brcmvirt_gpio_driver = {
+ .driver = {
+ .name = MODULE_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(brcmvirt_gpio_ids),
+ },
+ .probe = brcmvirt_gpio_probe,
+ .remove = brcmvirt_gpio_remove,
+};
+module_platform_driver(brcmvirt_gpio_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dom Cobley <popcornmix@gmail.com>");
+MODULE_DESCRIPTION("brcmvirt GPIO driver");
+MODULE_ALIAS("platform:brcmvirt-gpio");
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