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serial: 8250_platform: Enable generic 16550A platform devices

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Currently, 8250_platform driver is used only for devices with fixed
serial ports (plat_serial8250_port). Extend this driver for any generic
16550A platform devices which can be probed using standard hardware
discovery mechanisms like ACPI.

This is required in particular for RISC-V which has non-PNP generic
16550A compatible UART that needs to be enumerated as ACPI platform
device.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20240730051218.767580-1-sunilvl@ventanamicro.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sunil V L 2024-07-30 10:42:18 +05:30 committed by Greg Kroah-Hartman
parent 755ed2f303
commit d9e5a0ce2f
1 changed files with 77 additions and 0 deletions
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77
drivers/tty/serial/8250/8250_platform.c
View File

@ -6,7 +6,9 @@
* PNP 8250/16550 ports * PNP 8250/16550 ports
* "serial8250" platform devices * "serial8250" platform devices
*/ */
#include <linux/acpi.h>
#include <linux/array_size.h> #include <linux/array_size.h>
#include <linux/io.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/moduleparam.h> #include <linux/moduleparam.h>
#include <linux/once.h> #include <linux/once.h>
@ -100,6 +102,65 @@ void __init serial8250_isa_init_ports(void)
DO_ONCE(__serial8250_isa_init_ports); DO_ONCE(__serial8250_isa_init_ports);
} }
/*
* Generic 16550A platform devices
*/
static int serial8250_platform_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct uart_8250_port uart = { 0 };
struct resource *regs;
unsigned char iotype;
int ret, line;
regs = platform_get_resource(pdev, IORESOURCE_IO, 0);
if (regs) {
uart.port.iobase = regs->start;
iotype = UPIO_PORT;
} else {
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!regs) {
dev_err(dev, "no registers defined\n");
return -EINVAL;
}
uart.port.mapbase = regs->start;
uart.port.mapsize = resource_size(regs);
uart.port.flags = UPF_IOREMAP;
iotype = UPIO_MEM;
}
/* Default clock frequency*/
uart.port.uartclk = 1843200;
uart.port.type = PORT_16550A;
uart.port.dev = &pdev->dev;
uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
ret = uart_read_and_validate_port_properties(&uart.port);
/* no interrupt -> fall back to polling */
if (ret == -ENXIO)
ret = 0;
if (ret)
return ret;
if (uart.port.mapbase) {
uart.port.membase = devm_ioremap(dev, uart.port.mapbase, uart.port.mapsize);
if (!uart.port.membase)
return -ENOMEM;
}
/*
* The previous call may not set iotype correctly when reg-io-width
* property is absent and it doesn't support IO port resource.
*/
uart.port.iotype = iotype;
line = serial8250_register_8250_port(&uart);
if (line < 0)
return -ENODEV;
return 0;
}
/* /*
* Register a set of serial devices attached to a platform device. The * Register a set of serial devices attached to a platform device. The
* list is terminated with a zero flags entry, which means we expect * list is terminated with a zero flags entry, which means we expect
@ -110,6 +171,15 @@ static int serial8250_probe(struct platform_device *dev)
struct plat_serial8250_port *p = dev_get_platdata(&dev->dev); struct plat_serial8250_port *p = dev_get_platdata(&dev->dev);
struct uart_8250_port uart; struct uart_8250_port uart;
int ret, i, irqflag = 0; int ret, i, irqflag = 0;
struct fwnode_handle *fwnode = dev_fwnode(&dev->dev);
/*
* Probe platform UART devices defined using standard hardware
* discovery mechanism like ACPI or DT. Support only ACPI based
* serial device for now.
*/
if (!p && is_acpi_node(fwnode))
return serial8250_platform_probe(dev);
memset(&uart, 0, sizeof(uart)); memset(&uart, 0, sizeof(uart));
@ -198,6 +268,12 @@ static int serial8250_resume(struct platform_device *dev)
return 0; return 0;
} }
static const struct acpi_device_id acpi_platform_serial_table[] = {
{ "RSCV0003", 0 }, // RISC-V Generic 16550A UART
{ },
};
MODULE_DEVICE_TABLE(acpi, acpi_platform_serial_table);
static struct platform_driver serial8250_isa_driver = { static struct platform_driver serial8250_isa_driver = {
.probe = serial8250_probe, .probe = serial8250_probe,
.remove_new = serial8250_remove, .remove_new = serial8250_remove,
@ -205,6 +281,7 @@ static struct platform_driver serial8250_isa_driver = {
.resume = serial8250_resume, .resume = serial8250_resume,
.driver = { .driver = {
.name = "serial8250", .name = "serial8250",
.acpi_match_table = ACPI_PTR(acpi_platform_serial_table),
}, },
}; };