diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_loongson.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_loongson.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_loongson.c b/drivers/tty/serial/8250/8250_loongson.c new file mode 100644 index 000000000000..53153a116c01 --- /dev/null +++ b/drivers/tty/serial/8250/8250_loongson.c @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Serial Port driver for Loongson family chips + * + * Copyright (C) 2020-2025 Loongson Technology Corporation Limited + */ + +#include <linux/bitfield.h> +#include <linux/bits.h> +#include <linux/clk.h> +#include <linux/console.h> +#include <linux/module.h> +#include <linux/io.h> +#include <linux/property.h> +#include <linux/math.h> +#include <linux/mod_devicetable.h> +#include <linux/pm.h> +#include <linux/reset.h> + +#include "8250.h" + +/* Divisor Latch Fraction Register */ +#define LOONGSON_UART_DLF 0x2 + +#define LOONGSON_QUOT_FRAC_MASK GENMASK(7, 0) +#define LOONGSON_QUOT_DIV_MASK GENMASK(15, 8) + +struct loongson_uart_ddata { + bool has_frac; + u8 mcr_invert; + u8 msr_invert; +}; + +static const struct loongson_uart_ddata ls2k0500_uart_data = { + .has_frac = false, + .mcr_invert = UART_MCR_RTS | UART_MCR_DTR, + .msr_invert = UART_MSR_CTS | UART_MSR_DSR, +}; + +static const struct loongson_uart_ddata ls2k1500_uart_data = { + .has_frac = true, + .mcr_invert = UART_MCR_RTS | UART_MCR_DTR, + .msr_invert = 0, +}; + +struct loongson_uart_priv { + int line; + struct clk *clk; + struct resource *res; + struct reset_control *rst; + const struct loongson_uart_ddata *ddata; +}; + +static u8 serial_fixup(struct uart_port *p, unsigned int offset, u8 val) +{ + struct loongson_uart_priv *priv = p->private_data; + + switch (offset) { + case UART_MCR: + return val ^ priv->ddata->mcr_invert; + case UART_MSR: + return val ^ priv->ddata->msr_invert; + default: + return val; + } +} + +static u32 loongson_serial_in(struct uart_port *p, unsigned int offset) +{ + u8 val; + + val = readb(p->membase + (offset << p->regshift)); + + return serial_fixup(p, offset, val); +} + +static void loongson_serial_out(struct uart_port *p, unsigned int offset, unsigned int value) +{ + u8 val; + + offset <<= p->regshift; + val = serial_fixup(p, offset, value); + writeb(val, p->membase + offset); +} + +static unsigned int loongson_frac_get_divisor(struct uart_port *port, unsigned int baud, + unsigned int *frac) +{ + unsigned int quot; + + quot = DIV_ROUND_CLOSEST((port->uartclk << 4), baud); + *frac = FIELD_GET(LOONGSON_QUOT_FRAC_MASK, quot); + + return FIELD_GET(LOONGSON_QUOT_DIV_MASK, quot); +} + +static void loongson_frac_set_divisor(struct uart_port *port, unsigned int baud, + unsigned int quot, unsigned int quot_frac) +{ + struct uart_8250_port *up = up_to_u8250p(port); + + serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB); + serial_dl_write(up, quot); + serial_port_out(port, LOONGSON_UART_DLF, quot_frac); +} + +static int loongson_uart_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct uart_8250_port uart = {}; + struct loongson_uart_priv *priv; + struct uart_port *port; + int ret; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->ddata = device_get_match_data(dev); + + port = &uart.port; + spin_lock_init(&port->lock); + port->flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_IOREMAP; + port->iotype = UPIO_MEM; + port->regshift = 0; + port->dev = dev; + port->type = PORT_16550A; + port->private_data = priv; + + port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &priv->res); + if (!port->membase) + return -ENOMEM; + + port->mapbase = priv->res->start; + port->mapsize = resource_size(priv->res); + port->serial_in = loongson_serial_in; + port->serial_out = loongson_serial_out; + + if (priv->ddata->has_frac) { + port->get_divisor = loongson_frac_get_divisor; + port->set_divisor = loongson_frac_set_divisor; + } + + ret = uart_read_port_properties(port); + if (ret) + return ret; + + if (!port->uartclk) { + priv->clk = devm_clk_get_enabled(dev, NULL); + if (IS_ERR(priv->clk)) + return dev_err_probe(dev, PTR_ERR(priv->clk), + "Unable to determine clock frequency!\n"); + port->uartclk = clk_get_rate(priv->clk); + } + + priv->rst = devm_reset_control_get_optional_shared(dev, NULL); + if (IS_ERR(priv->rst)) + return PTR_ERR(priv->rst); + + ret = reset_control_deassert(priv->rst); + if (ret) + return ret; + + ret = serial8250_register_8250_port(&uart); + if (ret < 0) { + reset_control_assert(priv->rst); + return ret; + } + + priv->line = ret; + platform_set_drvdata(pdev, priv); + + return 0; +} + +static void loongson_uart_remove(struct platform_device *pdev) +{ + struct loongson_uart_priv *priv = platform_get_drvdata(pdev); + + serial8250_unregister_port(priv->line); + reset_control_assert(priv->rst); +} + +static int loongson_uart_suspend(struct device *dev) +{ + struct loongson_uart_priv *priv = dev_get_drvdata(dev); + struct uart_8250_port *up = serial8250_get_port(priv->line); + + serial8250_suspend_port(priv->line); + + if (!uart_console(&up->port) || console_suspend_enabled) + clk_disable_unprepare(priv->clk); + + return 0; +} + +static int loongson_uart_resume(struct device *dev) +{ + struct loongson_uart_priv *priv = dev_get_drvdata(dev); + struct uart_8250_port *up = serial8250_get_port(priv->line); + int ret; + + if (!uart_console(&up->port) || console_suspend_enabled) { + ret = clk_prepare_enable(priv->clk); + if (ret) + return ret; + } + + serial8250_resume_port(priv->line); + + return 0; +} + +static DEFINE_SIMPLE_DEV_PM_OPS(loongson_uart_pm_ops, loongson_uart_suspend, + loongson_uart_resume); + +static const struct of_device_id loongson_uart_of_ids[] = { + { .compatible = "loongson,ls2k0500-uart", .data = &ls2k0500_uart_data }, + { .compatible = "loongson,ls2k1500-uart", .data = &ls2k1500_uart_data }, + { }, +}; +MODULE_DEVICE_TABLE(of, loongson_uart_of_ids); + +static struct platform_driver loongson_uart_driver = { + .probe = loongson_uart_probe, + .remove = loongson_uart_remove, + .driver = { + .name = "loongson-uart", + .pm = pm_ptr(&loongson_uart_pm_ops), + .of_match_table = loongson_uart_of_ids, + }, +}; + +module_platform_driver(loongson_uart_driver); + +MODULE_DESCRIPTION("Loongson UART driver"); +MODULE_AUTHOR("Loongson Technology Corporation Limited."); +MODULE_LICENSE("GPL"); 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