diff options
Diffstat (limited to 'board/nvidia/common/uart-spi-switch.c')
-rw-r--r-- | board/nvidia/common/uart-spi-switch.c | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/board/nvidia/common/uart-spi-switch.c b/board/nvidia/common/uart-spi-switch.c new file mode 100644 index 0000000..23aa0b9 --- /dev/null +++ b/board/nvidia/common/uart-spi-switch.c @@ -0,0 +1,138 @@ +/* + * Copyright (c) 2011 The Chromium OS Authors. + * + * 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 <common.h> +#include <ns16550.h> +#include <asm/gpio.h> +#include <asm/arch/pinmux.h> +#include <asm/arch/uart-spi-switch.h> +#include <asm/arch/tegra2.h> +#include <asm/arch/tegra2_spi.h> + + +/* position of the UART/SPI select switch */ +enum spi_uart_switch { + SWITCH_UNKNOWN, + SWITCH_SPI, + SWITCH_UART, + SWITCH_BOTH +}; + +/* Information about the spi/uart switch */ +struct spi_uart { + int gpio; /* GPIO to control switch */ + NS16550_t regs; /* Address of UART affected */ + u32 port; /* Port number of UART affected */ +}; + +static struct spi_uart local; +static enum spi_uart_switch switch_pos; /* Current switch position */ + + +static void get_config(struct spi_uart *config) +{ +#if defined CONFIG_SPI_CORRUPTS_UART + config->gpio = CONFIG_UART_DISABLE_GPIO; + config->regs = (NS16550_t)CONFIG_SPI_CORRUPTS_UART; + config->port = CONFIG_SPI_CORRUPTS_UART_NR; +#else + config->gpio = -1; +#endif +} + +/* + * Init the UART / SPI switch. This can be called before relocation so we must + * not access BSS. + */ +void gpio_early_init_uart(void) +{ + struct spi_uart config; + + get_config(&config); + if (config.gpio != -1) { + /* Cannot provide a label prior to relocation */ + gpio_request(config.gpio, NULL); + gpio_direction_output(config.gpio, 0); + } +} + +/* + * Configure the UART / SPI switch. + */ +void gpio_config_uart(void) +{ + get_config(&local); + if (local.gpio != -1) { + gpio_direction_output(local.gpio, 0); + switch_pos = SWITCH_UART; + } else { + /* + * If we're here we don't have a SPI switch; go ahead and + * enable the SPI now. We didn't in spi_init() so we wouldn't + * kill the UART. + */ + pinmux_set_func(PINGRP_GMC, PMUX_FUNC_SFLASH); + switch_pos = SWITCH_BOTH; + } +} + +static void spi_uart_switch(struct spi_uart *config, + enum spi_uart_switch new_pos) +{ + if (switch_pos == SWITCH_BOTH || new_pos == switch_pos) + return; + + /* if the UART was selected, allow it to drain */ + if (switch_pos == SWITCH_UART) + NS16550_drain(config->regs, config->port); + + /* We need to dynamically change the pinmux, shared w/UART RXD/CTS */ + pinmux_set_func(PINGRP_GMC, new_pos == SWITCH_SPI ? + PMUX_FUNC_SFLASH : PMUX_FUNC_UARTD); + + /* + * On Seaboard, MOSI/MISO are shared w/UART. + * Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity. + * Enable UART later (cs_deactivate) so we can use it for U-Boot comms. + */ + gpio_direction_output(config->gpio, new_pos == SWITCH_SPI); + switch_pos = new_pos; + + /* if the SPI was selected, clear any junk bytes in the UART */ + if (switch_pos == SWITCH_UART) { + /* TODO: What if it is part-way through clocking in junk? */ + udelay(100); + NS16550_clear(config->regs, config->port); + } +} + +void pinmux_select_uart(NS16550_t regs) +{ + /* Also prevents calling spi_uart_switch() before relocation */ + if (regs == local.regs) + spi_uart_switch(&local, SWITCH_UART); +} + +void pinmux_select_spi(void) +{ + spi_uart_switch(&local, SWITCH_SPI); +} |