/** * @file * @brief NS16550 Driver implementation * * FileName: drivers/serial/serial_ns16550.c * * NS16550 support * Modified from u-boot drivers/serial.c and drivers/ns16550.c * originally from linux source (arch/ppc/boot/ns16550.c) * modified to use CFG_ISA_MEM and new defines */ /* * (C) Copyright 2008 * Texas Instruments, * Nishanth Menon * * (C) Copyright 2000 * Rob Taylor, Flying Pig Systems. robt@flyingpig.com. * * See file CREDITS for list of people who contributed to this * project. * * 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. * * 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. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA */ #include #include #include #include #include #include #include "serial_ns16550.h" #include /*********** Private Functions **********************************/ /** * @brief read register * * @param[in] cdev pointer to console device * @param[in] offset * * @return value */ static uint32_t ns16550_read(struct console_device *cdev, uint32_t off) { struct device_d *dev = cdev->dev; struct NS16550_plat *plat = (struct NS16550_plat *)dev->platform_data; int width = dev->resource[0].flags & IORESOURCE_MEM_TYPE_MASK; off <<= plat->shift; if (plat->reg_read) return plat->reg_read((unsigned long)dev->priv, off); switch (width) { case IORESOURCE_MEM_8BIT: return readb(dev->priv + off); case IORESOURCE_MEM_16BIT: return readw(dev->priv + off); case IORESOURCE_MEM_32BIT: return readl(dev->priv + off); } return -1; } /** * @brief write register * * @param[in] cdev pointer to console device * @param[in] offset * @param[in] val */ static void ns16550_write(struct console_device *cdev, uint32_t val, uint32_t off) { struct device_d *dev = cdev->dev; struct NS16550_plat *plat = (struct NS16550_plat *)dev->platform_data; int width = dev->resource[0].flags & IORESOURCE_MEM_TYPE_MASK; off <<= plat->shift; if (plat->reg_write) { plat->reg_write(val, (unsigned long)dev->priv, off); return; } switch (width) { case IORESOURCE_MEM_8BIT: writeb(val & 0xff, dev->priv + off); break; case IORESOURCE_MEM_16BIT: writew(val & 0xffff, dev->priv + off); break; case IORESOURCE_MEM_32BIT: writel(val, dev->priv + off); break; } } /** * @brief Compute the divisor for a baud rate * * @param[in] cdev pointer to console device * @param[in] baudrate baud rate * * @return divisor to be set */ static unsigned int ns16550_calc_divisor(struct console_device *cdev, unsigned int baudrate) { struct NS16550_plat *plat = (struct NS16550_plat *) cdev->dev->platform_data; unsigned int clk = plat->clock; return (clk / MODE_X_DIV / baudrate); } /** * @brief Initialize the device * * @param[in] cdev pointer to console device */ static void ns16550_serial_init_port(struct console_device *cdev) { unsigned int baud_divisor; /* Setup the serial port with the defaults first */ baud_divisor = ns16550_calc_divisor(cdev, CONFIG_BAUDRATE); /* initializing the device for the first time */ ns16550_write(cdev, 0x00, ier); #ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS ns16550_write(cdev, 0x07, mdr1); /* Disable */ #endif ns16550_write(cdev, LCR_BKSE | LCRVAL, lcr); ns16550_write(cdev, baud_divisor & 0xFF, dll); ns16550_write(cdev, (baud_divisor >> 8) & 0xff, dlm); ns16550_write(cdev, LCRVAL, lcr); ns16550_write(cdev, MCRVAL, mcr); ns16550_write(cdev, FCRVAL, fcr); #ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS ns16550_write(cdev, 0x00, mdr1); #endif } /*********** Exposed Functions **********************************/ /** * @brief Put a character to the serial port * * @param[in] cdev pointer to console device * @param[in] c character to put */ static void ns16550_putc(struct console_device *cdev, char c) { /* Loop Doing Nothing */ while ((ns16550_read(cdev, lsr) & LSR_THRE) == 0) ; ns16550_write(cdev, c, thr); } /** * @brief Retrieve a character from serial port * * @param[in] cdev pointer to console device * * @return return the character read */ static int ns16550_getc(struct console_device *cdev) { /* Loop Doing Nothing */ while ((ns16550_read(cdev, lsr) & LSR_DR) == 0) ; return ns16550_read(cdev, rbr); } /** * @brief Test if character is available * * @param[in] cdev pointer to console device * * @return - status based on data availability */ static int ns16550_tstc(struct console_device *cdev) { return ((ns16550_read(cdev, lsr) & LSR_DR) != 0); } /** * @brief Set the baudrate for the uart port * * @param[in] cdev console device * @param[in] baud_rate baud rate to set * * @return 0-implied to support the baudrate */ static int ns16550_setbaudrate(struct console_device *cdev, int baud_rate) { unsigned int baud_divisor = ns16550_calc_divisor(cdev, baud_rate); ns16550_write(cdev, 0x00, ier); ns16550_write(cdev, LCR_BKSE, lcr); ns16550_write(cdev, baud_divisor & 0xff, dll); ns16550_write(cdev, (baud_divisor >> 8) & 0xff, dlm); ns16550_write(cdev, LCRVAL, lcr); ns16550_write(cdev, MCRVAL, mcr); ns16550_write(cdev, FCRVAL, fcr); return 0; } /** * @brief Probe entry point -called on the first match for device * * @param[in] dev matched device * * @return EINVAL if platform_data is not populated, * ENOMEM if calloc failed * else return result of console_register */ static int ns16550_probe(struct device_d *dev) { struct console_device *cdev; struct NS16550_plat *plat = (struct NS16550_plat *)dev->platform_data; /* we do expect platform specific data */ if (plat == NULL) return -EINVAL; dev->priv = dev_request_mem_region(dev, 0); cdev = xzalloc(sizeof(*cdev)); dev->type_data = cdev; cdev->dev = dev; if (plat->f_caps) cdev->f_caps = plat->f_caps; else cdev->f_caps = CONSOLE_STDIN | CONSOLE_STDOUT | CONSOLE_STDERR; cdev->tstc = ns16550_tstc; cdev->putc = ns16550_putc; cdev->getc = ns16550_getc; cdev->setbrg = ns16550_setbaudrate; ns16550_serial_init_port(cdev); return console_register(cdev); } /** * @brief Driver registration structure */ static struct driver_d ns16550_serial_driver = { .name = "serial_ns16550", .probe = ns16550_probe, }; /** * @brief driver initialization function * * @return result of register_driver */ static int ns16550_serial_init(void) { return register_driver(&ns16550_serial_driver); } console_initcall(ns16550_serial_init);