On 05/05/2016 12:30 PM, Greg KH wrote:
> On Thu, May 05, 2016 at 06:23:12PM +0000, Andy Falanga (afalanga) wrote:
>> I'm writing my first serial driver for a UART (AXI UART Lite from
>> Xilinx). Yes, I know there's one in the kernel but the hardware in this
>> case isn't embedded.
>>
>> Using the documentation in <kernel_src>/Documentation/serial/driver and
>> the existing code for references, I've implemented my driver. However,
>> I cannot validate the my startup or request_port functions are being
>> called.
>>
>> I'm calling uart_register_driver() and then uart_register_port() and I'm
>> sure these functions are passing. I'm seeing my device handles show in
>> /dev. The documentation states that the startup() function, "... will
>> only be called when the port is initially opened." Yet, I'm not seeing
>> pr_info() messages that I should be. What should I look for in order to
>> determine why the setup functions aren't being called?
> Are you sure that some other driver isn't being called instead of yours?
>
> Without seeing the code, it's impossible to debug, please just send a
> patch.
>
>
Hi Greg,
I had to jump through some hoops in order to send the code. Here's what
I've got for driver registration/initialization.
#define MAX_SUPPORTED_UARTS 1
#define DRIVER_MAJOR_NUM 243 /* local/experimental */
#define DRIVER_MINOR_NUM 0
static int request_port(struct uart_port *);
static void release_port(struct uart_port *);
static int startup(struct uart_port *);
static void shutdown(struct uart_port *);
static struct uart_ops axilite_ops = {
.release_port = release_port,
.request_port = request_port,
.startup = startup,
.shutdown = shutdown,
};
static struct uart_port axilite_ports[MAX_SUPPORTED_UARTS] = {
{
.mapbase = 0, /* determined during discovery */
.membase = 0, /* calcuated after learning mapbase */
.iotype = UPIO_MEM, /* from serial_core.c */
.irq = 0, /* currently, device doesn't use an IRQ, just
polling */
.fifosize = 16, /* directly Xilinx documentation */
.ops = &axilite_ops,
.flags = UPF_FIXED_TYPE | UPF_FIXED_PORT | UPF_SPD_VHI,
.mctrl = TIOCM_CTS | TIOCM_DSR | TIOCM_CAR, /* from
uartlite.c in kernel tree */
},
};
static struct uart_driver axilite_driver = {
.owner = THIS_MODULE,
.driver_name = "axilite",
.dev_name = "ttyAUL",
.major = DRIVER_MAJOR_NUM,
.minor = DRIVER_MINOR_NUM,
.nr = MAX_SUPPORTED_UARTS,
};
static int startup(struct uart_port *pup)
{
void __iomem* pmem = pup->membase;
uint32_t ctlreg = 0;
pr_info("%s:%d entry point\n", __func__, __LINE__);
ctlreg = ioread32(CTL_REG_ADDR(pmem));
pr_info("DEBUG: %s:%d CTL Reg is 0x%08x\n",
__func__, __LINE__, ctlreg);
/* clear the FIFO's */
ctlreg |= CTL_REG_RST_TX | CTL_REG_RST_RX;
iowrite32(ctlreg, CTL_REG_ADDR(pmem));
return 0;
}
static void shutdown(struct uart_port *pup)
{
void __iomem* pmem = pup->membase;
pr_info("%s:%d entry point\n", __func__, __LINE__);
/* Using a queue from the axilite driver in the kernel */
iowrite32(0, CTL_REG_ADDR(pmem));
}
static void release_port(struct uart_port *pup)
{
pr_info("%s:%d entry point\n", __func__, __LINE__);
if (pup->membase)
iounmap(pup->membase);
pup->membase = NULL;
}
static int request_port(struct uart_port *pup)
{
int result = 0;
uint32_t bus_addr = pup->mapbase;
void __iomem* pmem = NULL;
pr_info("%s:%d mapping bus addr to virtual space\n",
__func__, __LINE__);
pmem = ioremap_nocache(bus_addr, UART_REGISTER_REGION);
if (IS_ERR_OR_NULL(pmem)) {
pr_err("%s:%d ioremap_nocache failed\n",
__func__, __LINE__);
result = PTR_ERR(pmem);
goto startup_exit;
}
pup->membase = pmem;
pr_info("%s:%d busaddr 0x%08x mapped to %p\n",
__func__, __LINE__, bus_addr, pmem);
startup_exit:
return result;
}
static int add_uart_ports(void)
{
int result = 0;
uint32_t i = 0, baseaddr = 0;
pr_info("%s:%d adding %d port(s) to the system\n",
__func__, __LINE__, uart_count);
/* calls into code which learns the base address,
* verified that it works
*/
baseaddr = get_uart_base(i);
if ((int)baseaddr == -EINVAL) {
pr_err("%s:%d Invalid index used\n", __func__, __LINE__);
result = (int)baseaddr;
goto add_ports_exit;
}
else if (0 == baseaddr) {
pr_err("%s:%d Invalid bus address encountered, port add
stopped\n",
__func__, __LINE__);
result = -ENODEV;
goto add_ports_exit;
}
else
axilite_port[i].mapbase = baseaddr;
result = uart_add_one_port(&axilite_driver, &axilite_port[i]);
if (result) {
pr_err("%s:%d uart_add_one_port failed for port %d\n",
__func__, __LINE__, i);
goto add_ports_exit;
}
/* TODO think of a better way to track whether the port
* is registered. this will work for now.
*/
axilite_port[i].private_data = &uart_count;
init_stage |= UART_PORT_REGISTERED;
add_ports_exit:
return result;
}
static int add_uart_driver(void)
{
int result = 0;
pr_info("%s:%d adding the driver\n", __func__, __LINE__);
uart_count = get_uart_count();
axilite_driver.nr = (int)uart_count;
result = uart_register_driver(&axilite_driver);
if (result) {
pr_err("%s:%d uart_register_driver failed\n",
__func__, __LINE__);
goto add_driver_exit;
}
init_stage |= DRIVER_REGISTERED;
add_driver_exit:
return result;
}
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