// SPDX-License-Identifier: GPL-2.0+ /* * Serial Port driver for Aspeed VUART device * * Copyright (C) 2016 Jeremy Kerr <[email protected]>, IBM Corp. * Copyright (C) 2006 Arnd Bergmann <[email protected]>, IBM Corp. */ #include <linux/device.h> #include <linux/module.h> #include <linux/of_address.h> #include <linux/of_irq.h> #include <linux/of_platform.h> #include <linux/regmap.h> #include <linux/mfd/syscon.h> #include <linux/tty.h> #include <linux/tty_flip.h> #include <linux/clk.h> #include "8250.h" #define ASPEED_VUART_GCRA … #define ASPEED_VUART_GCRA_VUART_EN … #define ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY … #define ASPEED_VUART_GCRA_DISABLE_HOST_TX_DISCARD … #define ASPEED_VUART_GCRB … #define ASPEED_VUART_GCRB_HOST_SIRQ_MASK … #define ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT … #define ASPEED_VUART_ADDRL … #define ASPEED_VUART_ADDRH … #define ASPEED_VUART_DEFAULT_LPC_ADDR … #define ASPEED_VUART_DEFAULT_SIRQ … #define ASPEED_VUART_DEFAULT_SIRQ_POLARITY … struct aspeed_vuart { … }; /* * If we fill the tty flip buffers, we throttle the data ready interrupt * to prevent dropped characters. This timeout defines how long we wait * to (conditionally, depending on buffer state) unthrottle. */ static const int unthrottle_timeout = …; /* * The VUART is basically two UART 'front ends' connected by their FIFO * (no actual serial line in between). One is on the BMC side (management * controller) and one is on the host CPU side. * * It allows the BMC to provide to the host a "UART" that pipes into * the BMC itself and can then be turned by the BMC into a network console * of some sort for example. * * This driver is for the BMC side. The sysfs files allow the BMC * userspace which owns the system configuration policy, to specify * at what IO port and interrupt number the host side will appear * to the host on the Host <-> BMC LPC bus. It could be different on a * different system (though most of them use 3f8/4). */ static inline u8 aspeed_vuart_readb(struct aspeed_vuart *vuart, u8 reg) { … } static inline void aspeed_vuart_writeb(struct aspeed_vuart *vuart, u8 val, u8 reg) { … } static ssize_t lpc_address_show(struct device *dev, struct device_attribute *attr, char *buf) { … } static int aspeed_vuart_set_lpc_address(struct aspeed_vuart *vuart, u32 addr) { … } static ssize_t lpc_address_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { … } static DEVICE_ATTR_RW(lpc_address); static ssize_t sirq_show(struct device *dev, struct device_attribute *attr, char *buf) { … } static int aspeed_vuart_set_sirq(struct aspeed_vuart *vuart, u32 sirq) { … } static ssize_t sirq_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { … } static DEVICE_ATTR_RW(sirq); static ssize_t sirq_polarity_show(struct device *dev, struct device_attribute *attr, char *buf) { … } static void aspeed_vuart_set_sirq_polarity(struct aspeed_vuart *vuart, bool polarity) { … } static ssize_t sirq_polarity_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { … } static DEVICE_ATTR_RW(sirq_polarity); static struct attribute *aspeed_vuart_attrs[] = …; static const struct attribute_group aspeed_vuart_attr_group = …; static void aspeed_vuart_set_enabled(struct aspeed_vuart *vuart, bool enabled) { … } static void aspeed_vuart_set_host_tx_discard(struct aspeed_vuart *vuart, bool discard) { … } static int aspeed_vuart_startup(struct uart_port *uart_port) { … } static void aspeed_vuart_shutdown(struct uart_port *uart_port) { … } static void __aspeed_vuart_set_throttle(struct uart_8250_port *up, bool throttle) { … } static void aspeed_vuart_set_throttle(struct uart_port *port, bool throttle) { … } static void aspeed_vuart_throttle(struct uart_port *port) { … } static void aspeed_vuart_unthrottle(struct uart_port *port) { … } static void aspeed_vuart_unthrottle_exp(struct timer_list *timer) { … } /* * Custom interrupt handler to manage finer-grained flow control. Although we * have throttle/unthrottle callbacks, we've seen that the VUART device can * deliver characters faster than the ldisc has a chance to check buffer space * against the throttle threshold. This results in dropped characters before * the throttle. * * We do this by checking for flip buffer space before RX. If we have no space, * throttle now and schedule an unthrottle for later, once the ldisc has had * a chance to drain the buffers. */ static int aspeed_vuart_handle_irq(struct uart_port *port) { … } static void aspeed_vuart_auto_configure_sirq_polarity( struct aspeed_vuart *vuart, struct device_node *syscon_np, u32 reg_offset, u32 reg_mask) { … } static int aspeed_vuart_map_irq_polarity(u32 dt) { … } static int aspeed_vuart_probe(struct platform_device *pdev) { … } static void aspeed_vuart_remove(struct platform_device *pdev) { … } static const struct of_device_id aspeed_vuart_table[] = …; MODULE_DEVICE_TABLE(of, aspeed_vuart_table); static struct platform_driver aspeed_vuart_driver = …; module_platform_driver(…) …; MODULE_AUTHOR(…) …; MODULE_LICENSE(…) …; MODULE_DESCRIPTION(…) …;
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