UART5 getty under Ubuntu Linux

[frankmiller]

Greetings,

I have a custom MX6 board where we've have a DB-9 serial connection on UART5.  We're running the most recent Ubuntu Linux on the system.  How can I configure the system to start a getty on that device at bootup?

Thanks,

FM

[jimmychan]

Please read the document BSP_Porting_Guide_L3.0.35_1.1.0.pdf. ( Chapter 3 -- Registering a New UART Driver )  for the details.  You can download the Linux BSP document bundle from here: http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=IMX6_SW

• Linux Bundle for i.MX 6Quad/Dual   ( for i.mx6Q/D)

[frankmiller]

Hi Jimmy,

Thanks for the reply.  I've done all of this and incorporated some other advice that was given to me on another thread.  So I have the following changes in board-mx6q_sabresd.c:

// <added>

static const struct imxuart_platform_data

  mx6_sabresd_uart4_data __initconst = {

  .flags = IMXUART_HAVE_RTSCTS | IMXUART_SDMA,

  .dma_req_rx = MX6Q_DMA_REQ_UART5_RX,

  .dma_req_tx = MX6Q_DMA_REQ_UART5_TX,

};

// </added>

static inline void mx6q_sabresd_init_uart(void)

{

        imx6q_add_imx_uart(0, NULL);

//      imx6q_add_imx_uart(2, NULL);

        imx6q_add_imx_uart(4, &mx6_sabresd_uart4_data);

//      imx6q_add_imx_uart(4, NULL);

//      imx6q_add_imx_uart(0, NULL);

}

This is the output I get when I try to boot this.  For some reason it doesnt appear to be applying these parameters to UART5.  The kernel boot hangs at this point as well.  Any thoughts?

imx-sdma imx-sdma: loaded firmware 1.1

imx-sdma imx-sdma: initialized

Serial: IMX driver

imx-uart.0: ttymxc0 at MMIO 0x2020000 (irq = 58) is a IMX

console [ttymxc0] enabled, bootconsole disabled

console [ttymxc0] enabled, bootconsole disabled

imx-uart.1: ttymxc1 at MMIO 0x2184200 (irq = 2) is a IMX

[jimmychan]

According to the Linux BSP reference manual (Linux_6DQ_RM_L3.0.35_1.1.0.pdf) Chapter 38 -- UART driver, there is a note (attach below) that DMA may be abnormal if not enable RTS/CTS. So please try to enable RTS/CTS.

NOTE :

If you want to use the DMA support for UART please also enable the RTS/CTS for it. The DMA may be abnormal if you do not enable the RTS/CTS.

[frankmiller]

In addition to the changes you mentioned, I've found I need to do the following changes as well.  First in linux/arch/arm/plat-mxc/include/mach/mx6.h:

// <added>

#define MX6Q_UART5_BASE_ADDR            0x021f4000

// </added>

I also had to add an entry in the ..._uart_data[] table for UART5 in linux/arch/arm/plat-mxc/devices/platform-imx-usrt.c:

#ifdef CONFIG_SOC_IMX6Q

const struct imx_imx_uart_1irq_data imx6q_imx_uart_data[] __initconst = {

#define imx6q_imx_uart_data_entry(_id, _hwid)                           \

        imx_imx_uart_1irq_data_entry(MX6Q, _id, _hwid, SZ_4K)

        imx6q_imx_uart_data_entry(0, 1),

        imx6q_imx_uart_data_entry(1, 2),

        imx6q_imx_uart_data_entry(2, 3),

        imx6q_imx_uart_data_entry(3, 4),

// <added>

        imx6q_imx_uart_data_entry(4, 5),

// </added>

};

#endif /* ifdef CONFIG_SOC_IMX6Q */

These two changes allow the kernel to boot but when I look at the kernel output I get this:

imx-uart.0: ttymxc0 at MMIO 0x20200000 (irq = 58) is a IMX

imx-uart: probe of imx-uart.4 failed with error -2

Any thoughts on this error code?

Thanks,

FM

[lily_zhang · Accepted solution]

So you hope to use UART5 as console output port. Right?

You can check the followings:

1. Ensure you have config UART5 relative pins.

2. Set early UART as UART5 if you hope to use UART5 as early console output.

uart_clk = clk_get_sys("imx-uart.4", NULL);

early_console_setup((UART5_BASE_ADDR, uart_clk);

3. Add UART5 device: imx6q_add_imx_uart(4, NULL).  If you have UART platform data, you should set accordingly. I saw your early mx6_sabresd_uart4_data __initconst is wrong. Because you mention you don't have RTS/CTS, but you enable it into the flags.

4. Then you can change your console output as UART5 into command line when you boot: console=ttymxc4.

5. For getty, you can check etc/init. If you don't want to modify getty, another method -  you can change  as       imx6q_imx_uart_data_entry(0, 5) in arch/arm/plat-mxc/devices/platform-imx-uart.c. Then use 0 for UART5 in other step 3 and 4.

[frankmiller]

This is the code I had to add to make this work but it is finally working!

diff board-mx6q_sabresd.h board-mx6q_sabresd.h.bak

44,46c44,45

< //    MX6Q_PAD_KEY_COL1__ECSPI1_MISO,

< //    MX6Q_PAD_KEY_ROW1__GPIO_4_9,

<

---

>     MX6Q_PAD_KEY_COL1__ECSPI1_MISO,

>     MX6Q_PAD_KEY_ROW1__GPIO_4_9,

182,191c181,182

< //    MX6Q_PAD_EIM_D24__UART3_TXD,

< //    MX6Q_PAD_EIM_D25__UART3_RXD,

<

< // <added>

<     /* UART5 for external serial port */

<     MX6Q_PAD_KEY_COL1__UART5_TXD,

<     MX6Q_PAD_KEY_ROW1__UART5_RXD,

<     MX6Q_PAD_KEY_COL4__UART5_RTS,

<     MX6Q_PAD_KEY_ROW4__UART5_CTS,

< // </added>

---

>     MX6Q_PAD_EIM_D24__UART3_TXD,

>     MX6Q_PAD_EIM_D25__UART3_RXD,

225,228c216,219

<     //MX6Q_PAD_SD3_DAT4__USDHC3_DAT4_50MHZ,

<     //MX6Q_PAD_SD3_DAT5__USDHC3_DAT5_50MHZ,

<     //MX6Q_PAD_SD3_DAT6__USDHC3_DAT6_50MHZ,

<     //MX6Q_PAD_SD3_DAT7__USDHC3_DAT7_50MHZ,

---

>     MX6Q_PAD_SD3_DAT4__USDHC3_DAT4_50MHZ,

>     MX6Q_PAD_SD3_DAT5__USDHC3_DAT5_50MHZ,

>     MX6Q_PAD_SD3_DAT6__USDHC3_DAT6_50MHZ,

>     MX6Q_PAD_SD3_DAT7__USDHC3_DAT7_50MHZ,

265c256

< //    MX6Q_PAD_KEY_COL4__GPIO_4_14, /* PCIE_DIS */

---

>     MX6Q_PAD_KEY_COL4__GPIO_4_14, /* PCIE_DIS */

diff board-mx6q_sabresd.c board-mx6q_sabresd.c.bak

249a249

>     imx6q_add_imx_uart(2, NULL);

251d250

< //    imx6q_add_imx_uart(2, NULL);

1919,1923c1918,1919

< //    uart_clk = clk_get_sys("imx-uart.0", NULL);

<     uart_clk = clk_get_sys("imx-uart.4", NULL);

<

< //    early_console_setup(UART1_BASE_ADDR, uart_clk);

<     early_console_setup(UART5_BASE_ADDR, uart_clk);

---

>     uart_clk = clk_get_sys("imx-uart.0", NULL);

>     early_console_setup(UART1_BASE_ADDR, uart_clk);

diff platform-imx-uart.c platform-imx-uart.c.bak

133,139c133,136

<

< //    imx6q_imx_uart_data_entry(0, 1),

<     imx6q_imx_uart_data_entry(0, 5),

<

< //    imx6q_imx_uart_data_entry(1, 2),

< //    imx6q_imx_uart_data_entry(2, 3),

< //    imx6q_imx_uart_data_entry(3, 4),

---

>     imx6q_imx_uart_data_entry(0, 1),

>     imx6q_imx_uart_data_entry(1, 2),

>     imx6q_imx_uart_data_entry(2, 3),

>     imx6q_imx_uart_data_entry(3, 4),

diff mx6.h mx6.h.bak

286,290d285

<

< // <added>

< #define MX6Q_UART5_BASE_ADDR        0x021f4000

< // </added>

<

494,498d488

<

< // <added>

< #define MX6Q_INT_UART5            MXC_INT_UART5_ANDED

< // </added>

<

[frankmiller]

I've seen this note.  Is there anyway to bring up a UART without RTS/CTS?  UART1 on this board has only the TX/RX lines connected.  I'm getting a login prompt on that port but cannot input anything to it from minicom on a Linux laptop.

Thanks,

FM