| Message ID | 20240730051218.767580-1-sunilvl@ventanamicro.com |
|---|---|
| State | New |
| Headers | show |
| Series | serial: 8250_platform: Enable generic 16550A platform devices | expand |
On Mon, 29 Jul 2024 22:12:18 PDT (-0700), Sunil V L wrote: > 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> > --- > drivers/tty/serial/8250/8250_platform.c | 77 +++++++++++++++++++++++++ > 1 file changed, 77 insertions(+) It seems a bit awkward that we need something RISC-V specific here. I guess the idea is that we don't want to depend on PNP because we'd end up with a bunch of PCI dependencies as well? That seems like kind of an odd way to do things, but I'm frequently suprised by ACPI stuff so Acked-by: Palmer Dabbelt <palmer@rivosinc.com> if someone was waiting for me... > diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c > index d5c8d851348d..bdfb16bed4f2 100644 > --- a/drivers/tty/serial/8250/8250_platform.c > +++ b/drivers/tty/serial/8250/8250_platform.c > @@ -6,7 +6,9 @@ > * PNP 8250/16550 ports > * "serial8250" platform devices > */ > +#include <linux/acpi.h> > #include <linux/array_size.h> > +#include <linux/io.h> > #include <linux/module.h> > #include <linux/moduleparam.h> > #include <linux/once.h> > @@ -100,6 +102,65 @@ void __init serial8250_isa_init_ports(void) > 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 > * 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 uart_8250_port uart; > 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)); > > @@ -198,6 +268,12 @@ static int serial8250_resume(struct platform_device *dev) > 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 = { > .probe = serial8250_probe, > .remove_new = serial8250_remove, > @@ -205,6 +281,7 @@ static struct platform_driver serial8250_isa_driver = { > .resume = serial8250_resume, > .driver = { > .name = "serial8250", > + .acpi_match_table = ACPI_PTR(acpi_platform_serial_table), > }, > };
On Tue, Sep 17, 2024 at 06:10:25AM -0700, Palmer Dabbelt wrote: > On Mon, 29 Jul 2024 22:12:18 PDT (-0700), Sunil V L wrote: > > 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. > It seems a bit awkward that we need something RISC-V specific here. I > guess the idea is that we don't want to depend on PNP because we'd end > up with a bunch of PCI dependencies as well? That seems like kind of an > odd way to do things, but I'm frequently suprised by ACPI stuff so We have the same for HSUART on Intel (see 8250_dw.c). The ACPI devices use different approach than PNP. PNP has the exact requirements for compatibility with the legacy UARTs (to some extend). It puts some limitations. I believe having specifics for RISC-V is fine. But I haven't checked the real IP used in the SoC. If it's one that we have the existing driver for (like again mentioned 8250_dw.c), then it should be added there. TL;DR: so, what is the IP is in hardware for UART? Custom?
diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c index d5c8d851348d..bdfb16bed4f2 100644 --- a/drivers/tty/serial/8250/8250_platform.c +++ b/drivers/tty/serial/8250/8250_platform.c @@ -6,7 +6,9 @@ * PNP 8250/16550 ports * "serial8250" platform devices */ +#include <linux/acpi.h> #include <linux/array_size.h> +#include <linux/io.h> #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/once.h> @@ -100,6 +102,65 @@ void __init serial8250_isa_init_ports(void) 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 * 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 uart_8250_port uart; 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)); @@ -198,6 +268,12 @@ static int serial8250_resume(struct platform_device *dev) 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 = { .probe = serial8250_probe, .remove_new = serial8250_remove, @@ -205,6 +281,7 @@ static struct platform_driver serial8250_isa_driver = { .resume = serial8250_resume, .driver = { .name = "serial8250", + .acpi_match_table = ACPI_PTR(acpi_platform_serial_table), }, };
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> --- drivers/tty/serial/8250/8250_platform.c | 77 +++++++++++++++++++++++++ 1 file changed, 77 insertions(+)