diff options
Diffstat (limited to 'drivers/misc/aspeed-uart-routing.c')
| -rw-r--r-- | drivers/misc/aspeed-uart-routing.c | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/drivers/misc/aspeed-uart-routing.c b/drivers/misc/aspeed-uart-routing.c new file mode 100644 index 000000000000..1fd5556e69a0 --- /dev/null +++ b/drivers/misc/aspeed-uart-routing.c @@ -0,0 +1,404 @@ +/* + * UART Routing driver for Aspeed AST2500 + * + * Copyright (c) 2018 Google LLC + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ +#include <linux/device.h> +#include <linux/module.h> +#include <linux/of_address.h> +#include <linux/of_platform.h> + +/* The Aspeed AST2500 allows to dynamically route the inputs for the built-in + * UARTS and physical serial I/O ports. + * + * This allows, for example, to connect the output of UART to another UART. + * This can be used to enable host<->BMC communication via UARTs, e.g. to allow + * access to the host's serial console. + * + * This driver is for the BMC side. The sysfs files allow the BMC userspace + * which owns the system configuration policy, to configure how UARTs and + * physical serial I/O ports are routed. + */ + +#define ASPEED_HICRA_IO1 "io1" +#define ASPEED_HICRA_IO2 "io2" +#define ASPEED_HICRA_IO3 "io3" +#define ASPEED_HICRA_IO4 "io4" +#define ASPEED_HICRA_IO5 "io5" +#define ASPEED_HICRA_IO6 "io6" +#define ASPEED_HICRA_UART1 "uart1" +#define ASPEED_HICRA_UART2 "uart2" +#define ASPEED_HICRA_UART3 "uart3" +#define ASPEED_HICRA_UART4 "uart4" +#define ASPEED_HICRA_UART5 "uart5" +#define ASPEED_HICRA_RAW "raw" + +struct aspeed_uart_routing { + struct device *dev; + void __iomem *regs; + spinlock_t lock; +}; + +struct aspeed_uart_routing_selector { + struct device_attribute dev_attr; + int shift; + int mask; + const char * const options[]; +}; + +#define to_routing_selector(_dev_attr) \ + container_of(_dev_attr, struct aspeed_uart_routing_selector, dev_attr) + + +static ssize_t aspeed_uart_routing_show(struct device *dev, + struct device_attribute *attr, + char *buf); + +static ssize_t aspeed_uart_routing_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count); + +#define ROUTING_ATTR(_name) { \ + .attr = {.name = _name, \ + .mode = VERIFY_OCTAL_PERMISSIONS(S_IWUSR | S_IRUGO) }, \ + .show = aspeed_uart_routing_show, \ + .store = aspeed_uart_routing_store, \ +} + +static struct aspeed_uart_routing_selector raw_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_RAW), + .shift = 0, + .mask = 0xffffffff, + .options = { + NULL // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector uart5_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_UART5), + .shift = 28, + .mask = 0xf, + .options = { + ASPEED_HICRA_IO5, // 0 + ASPEED_HICRA_IO1, // 1 + ASPEED_HICRA_IO2, // 2 + ASPEED_HICRA_IO3, // 3 + ASPEED_HICRA_IO4, // 4 + ASPEED_HICRA_UART1, // 5 + ASPEED_HICRA_UART2, // 6 + ASPEED_HICRA_UART3, // 7 + ASPEED_HICRA_UART4, // 8 + ASPEED_HICRA_IO6, // 9 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector uart4_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_UART4), + .shift = 25, + .mask = 0x7, + .options = { + ASPEED_HICRA_IO4, // 0 + ASPEED_HICRA_IO1, // 1 + ASPEED_HICRA_IO2, // 2 + ASPEED_HICRA_IO3, // 3 + ASPEED_HICRA_UART1, // 4 + ASPEED_HICRA_UART2, // 5 + ASPEED_HICRA_UART3, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector uart3_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_UART3), + .shift = 22, + .mask = 0x7, + .options = { + ASPEED_HICRA_IO3, // 0 + ASPEED_HICRA_IO4, // 1 + ASPEED_HICRA_IO1, // 2 + ASPEED_HICRA_IO2, // 3 + ASPEED_HICRA_UART4, // 4 + ASPEED_HICRA_UART1, // 5 + ASPEED_HICRA_UART2, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector uart2_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_UART2), + .shift = 19, + .mask = 0x7, + .options = { + ASPEED_HICRA_IO2, // 0 + ASPEED_HICRA_IO3, // 1 + ASPEED_HICRA_IO4, // 2 + ASPEED_HICRA_IO1, // 3 + ASPEED_HICRA_UART3, // 4 + ASPEED_HICRA_UART4, // 5 + ASPEED_HICRA_UART1, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector uart1_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_UART1), + .shift = 16, + .mask = 0x7, + .options = { + ASPEED_HICRA_IO1, // 0 + ASPEED_HICRA_IO2, // 1 + ASPEED_HICRA_IO3, // 2 + ASPEED_HICRA_IO4, // 3 + ASPEED_HICRA_UART2, // 4 + ASPEED_HICRA_UART3, // 5 + ASPEED_HICRA_UART4, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector io5_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_IO5), + .shift = 12, + .mask = 0x7, + .options = { + ASPEED_HICRA_UART5, // 0 + ASPEED_HICRA_UART1, // 1 + ASPEED_HICRA_UART2, // 2 + ASPEED_HICRA_UART3, // 3 + ASPEED_HICRA_UART4, // 4 + ASPEED_HICRA_IO1, // 5 + ASPEED_HICRA_IO3, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector io4_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_IO4), + .shift = 9, + .mask = 0x7, + .options = { + ASPEED_HICRA_UART4, // 0 + ASPEED_HICRA_UART5, // 1 + ASPEED_HICRA_UART1, // 2 + ASPEED_HICRA_UART2, // 3 + ASPEED_HICRA_UART3, // 4 + ASPEED_HICRA_IO1, // 5 + ASPEED_HICRA_IO2, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector io3_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_IO3), + .shift = 6, + .mask = 0x7, + .options = { + ASPEED_HICRA_UART3, // 0 + ASPEED_HICRA_UART4, // 1 + ASPEED_HICRA_UART5, // 2 + ASPEED_HICRA_UART1, // 3 + ASPEED_HICRA_UART2, // 4 + ASPEED_HICRA_IO1, // 5 + ASPEED_HICRA_IO2, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector io2_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_IO2), + .shift = 3, + .mask = 0x7, + .options = { + ASPEED_HICRA_UART2, // 0 + ASPEED_HICRA_UART3, // 1 + ASPEED_HICRA_UART4, // 2 + ASPEED_HICRA_UART5, // 3 + ASPEED_HICRA_UART1, // 4 + ASPEED_HICRA_IO3, // 5 + ASPEED_HICRA_IO4, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + +static struct aspeed_uart_routing_selector io1_sel = { + .dev_attr = ROUTING_ATTR(ASPEED_HICRA_IO1), + .shift = 0, + .mask = 0x7, + .options = { + ASPEED_HICRA_UART1, // 0 + ASPEED_HICRA_UART2, // 1 + ASPEED_HICRA_UART3, // 2 + ASPEED_HICRA_UART4, // 3 + ASPEED_HICRA_UART5, // 4 + ASPEED_HICRA_IO3, // 5 + ASPEED_HICRA_IO4, // 6 + ASPEED_HICRA_IO6, // 7 + NULL, // NULL termination + }, +}; + + +static struct attribute *aspeed_uart_routing_attrs[] = { + &uart1_sel.dev_attr.attr, + &uart2_sel.dev_attr.attr, + &uart3_sel.dev_attr.attr, + &uart4_sel.dev_attr.attr, + &uart5_sel.dev_attr.attr, + &io1_sel.dev_attr.attr, + &io2_sel.dev_attr.attr, + &io3_sel.dev_attr.attr, + &io4_sel.dev_attr.attr, + &io5_sel.dev_attr.attr, + &raw_sel.dev_attr.attr, + NULL, +}; + +static const struct attribute_group aspeed_uart_routing_attr_group = { + .attrs = aspeed_uart_routing_attrs, +}; + +static ssize_t aspeed_uart_routing_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev); + struct aspeed_uart_routing_selector *sel = to_routing_selector(attr); + int val, pos, len = 0; + + val = (readl(uart_routing->regs) >> sel->shift) & sel->mask; + + if (sel == &raw_sel) { + len += snprintf(buf, PAGE_SIZE - 1, "0x%08x\n", val); + } else { + for (pos = 0; sel->options[pos] != NULL; ++pos) { + if (pos == val) { + len += snprintf(buf + len, PAGE_SIZE - 1 - len, + "[%s] ", sel->options[pos]); + } else { + len += snprintf(buf + len, PAGE_SIZE - 1 - len, + "%s ", sel->options[pos]); + } + } + + if (val >= pos) { + len += snprintf(buf + len, PAGE_SIZE - 1 - len, + "[unknown(%d)]", val); + } + + len += snprintf(buf + len, PAGE_SIZE - 1 - len, "\n"); + } + + return len; +} + +static ssize_t aspeed_uart_routing_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev); + struct aspeed_uart_routing_selector *sel = to_routing_selector(attr); + int val, res; + char end; + u32 reg; + + if (sel == &raw_sel) { + res = sscanf(buf, "%i%c", &val, &end); + if (res < 1 || (res > 1 && end != '\n')) + return -EINVAL; + } else { + val = match_string(sel->options, -1, buf); + if (val < 0) { + dev_err(dev, "invalid value \"%s\"\n", buf); + return -EINVAL; + } + } + + spin_lock(&uart_routing->lock); + reg = readl(uart_routing->regs); + // Zero out existing value in specified bits. + reg &= ~(sel->mask << sel->shift); + // Set new value in specified bits. + reg |= (val & sel->mask) << sel->shift; + writel(reg, uart_routing->regs); + spin_unlock(&uart_routing->lock); + + return count; +} + +static int aspeed_uart_routing_probe(struct platform_device *pdev) +{ + struct aspeed_uart_routing *uart_routing; + struct resource *res; + int rc; + + uart_routing = devm_kzalloc(&pdev->dev, + sizeof(*uart_routing), + GFP_KERNEL); + if (!uart_routing) + return -ENOMEM; + + spin_lock_init(&uart_routing->lock); + uart_routing->dev = &pdev->dev; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + uart_routing->regs = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(uart_routing->regs)) + return PTR_ERR(uart_routing->regs); + + rc = sysfs_create_group(&uart_routing->dev->kobj, + &aspeed_uart_routing_attr_group); + if (rc < 0) + return rc; + + platform_set_drvdata(pdev, uart_routing); + + return 0; +} + +static int aspeed_uart_routing_remove(struct platform_device *pdev) +{ + struct aspeed_uart_routing *uart_routing = platform_get_drvdata(pdev); + + sysfs_remove_group(&uart_routing->dev->kobj, + &aspeed_uart_routing_attr_group); + + return 0; +} + +static const struct of_device_id aspeed_uart_routing_table[] = { + { .compatible = "aspeed,ast2500-uart-routing" }, + { }, +}; + +static struct platform_driver aspeed_uart_routing_driver = { + .driver = { + .name = "aspeed-uart-routing", + .of_match_table = aspeed_uart_routing_table, + }, + .probe = aspeed_uart_routing_probe, + .remove = aspeed_uart_routing_remove, +}; + +module_platform_driver(aspeed_uart_routing_driver); + +MODULE_AUTHOR("Oskar Senft <osk@google.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("Driver to configure Aspeed UART routing"); |