Forums » Software Development »
MAX3100 (SPI to UART bridge) driver not working
Added by Zhe Ji almost 10 years ago
Hello,
We are trying to compile the driver for MAX3100 and we are unable to get the node /dev/ttyMAX in spite of these changes:
1. Changed baseboard-mityarm335x-devkit-3359.c to the following:
#include <linux/serial_max3100.h>
static __init void baseboard_setup_spi0_devices(void)
{
setup_pin_mux(spi0_pin_mux);
spi_register_board_info(baseboard_spi0_slave_info,
ARRAY_SIZE(baseboard_spi0_slave_info));
//baseboard_setup_audio();
//baseboard_setup_ts();
}
static struct spi_board_info baseboard_spi0_slave_info[] = {
{
.modalias = "spi:max3100",
.controller_data = &spi0_ctlr_data,
.platform_data = &max3100_plat_data,
.irq = IRQ_EINT12,
.max_speed_hz = 5*1000*1000,
.bus_num = 0,
.chip_select = 0,
.mode = SPI_MODE_0,
},
2. Went into Linux menuconfig and enabled support for MAX3100 chip (device drivers --> character devices --> serial --> MAX3100)
We changed the max3100.c to print some things in the boot log, and its says that the __init max3100_init(void) is being executed and is fine.
But we still can't see the "/dev"ttyMAX" it is supposed to create.
Any suggestions?
Bindu
Replies (3)
RE: MAX3100 (SPI to UART bridge) driver not working - Added by Jonathan Cormier almost 10 years ago
The init driver gets called when the driver is added to the kernel. If its built in then this happens early on, if its built as a module then this happens when you insert the module. The probe function gets called when the driver gets tied to a device and thus should be getting called when you run the spi_register... call. If you aren't seeing the probe then that usually indicates your modalias is incorrect.
Looking at the max3100.c file and searching for a name string I get two possible names. "ttyMAX" and "max3100". If I recall correctly using the .driver.name wasn't the correct name for other drivers i've used in the past. So I would start by trying the "ttyMAX" name first. Make sure to check for your print statment in the max3100_probe function to verify if you've gotten the correct name.
static struct uart_driver max3100_uart_driver = {
.owner = THIS_MODULE,
.driver_name = "ttyMAX",
.dev_name = "ttyMAX",
.major = MAX3100_MAJOR,
.minor = MAX3100_MINOR,
.nr = MAX_MAX3100,
};
static struct spi_driver max3100_driver = {
.driver = {
.name = "max3100",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = max3100_probe,
.remove = __devexit_p(max3100_remove),
.suspend = max3100_suspend,
.resume = max3100_resume,
};
RE: MAX3100 (SPI to UART bridge) driver not working - Added by Bindu Jagannatha almost 10 years ago
Jonathan,
Thank you for the answer; using the following helped with respect to creating the /dev/ttyMAX0:
static struct spi_board_info baseboard_spi0_slave_info[] = {
{
.modalias = "max3100",
.controller_data = &spi0_ctlr_data,
.platform_data = &max3100_plat_data,
.irq = -1,
.max_speed_hz = 5*1000*1000,
.bus_num = 1,
.chip_select = 1,
.mode = SPI_MODE_0,
},
However, it goes into kernel oops when I try to test a small program on the port. Is it due to the value of .irq? How does one decide what value that should be (the max3100.c said use IRQ_EINT12, but that doesn't exist).
Bindu
RE: MAX3100 (SPI to UART bridge) driver not working - Added by Jonathan Cormier almost 10 years ago
Bindu,
You can look at how the other baseboard_spi0_slave_info have the irq filled in. Its possible that simply not setting the value might be the correct action.
