SPI TC4C123GH6PM query

I have written code for SPI, freescale mode. using driverlib 2.1.1.71 & keil 5.13.0.0.

1. I don't want to use SSI0Fss. Since I have two SPi slaves connected, so selecting two GPIo fro CS select purpose.
I didn't configure the Fss pin in code. is it enough to do so?


2. Page 965 of tm4c123gh6pm, says that pull-ups can be used on SPI to avoid any wrong state.
Do I should make pull-ups on all three pins clk, miso, mosi in any mode0-3
Or I should use pull-down in mode0 for clock?
Or I should use pull-ups only irrespective of mode.

Is below method correct to configure pull-ups
HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) = HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) | REG32_BIT_5;

3. In peripheral lib, SSIIntEnable() has four int flags: SSI_TXFF, SSI_RXFF, SSI_RXTO, or SSI_RXOR.
while SSIIntClear() has only two clear flags: SSI_RXTO , SSI_RXOR.
Does Tx flags automatically cleared by hardware?

4. How to diable fifo in SSI.
I want to transmit/receive only last byte written.

5. I have written code for SPI below in loopback mode & using AHB base for gpio pins.
I have checked on tm4c123gxl lauchpad & its working.
Is it ok ?

/* enable SSI0 module */    
    SysCtlPeripheralDisable(SYSCTL_PERIPH_SSI0);
    SysCtlPeripheralReset(SYSCTL_PERIPH_SSI0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);
    while( (!(SysCtlPeripheralReady(SYSCTL_PERIPH_SSI0)))  &&  (--ready_count));
    if(0U == ready_count)   /* if periph not ready take action */
    {
    }        
    
/* enable clk */
    SysCtlGPIOAHBEnable(SYSCTL_PERIPH_GPIOA);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
    while( (!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOA)))  &&  (--ready_count));
    if(0U == ready_count)   /* if periph not ready take action */
    {
    }      
    GPIOPinConfigure(GPIO_PA2_SSI0CLK);
    GPIOPinTypeSSI(GPIO_PORTA_AHB_BASE , GPIO_PIN_2);
    HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) = HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) | REG32_BIT_5;
    
/* enable rx */
    GPIOPinConfigure(GPIO_PA4_SSI0RX);
    GPIOPinTypeSSI(GPIO_PORTA_AHB_BASE , GPIO_PIN_4);    
    HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) = HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) | REG32_BIT_5;
    
/* enable tx */  
    GPIOPinConfigure(GPIO_PA5_SSI0TX);
    GPIOPinTypeSSI(GPIO_PORTA_AHB_BASE , GPIO_PIN_5);       
    HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) = HWREG(GPIO_PORTA_AHB_BASE + GPIO_O_PUR) | REG32_BIT_5;
    
/* disable SPi first */ 
    SSIDisable(SSI0_BASE);
    SSIDMADisable(SSI0_BASE , SSI_DMA_RX | SSI_DMA_TX);
    SSIIntDisable(SSI0_BASE , SSI_TXFF | SSI_RXFF | SSI_RXTO | SSI_RXOR);
    SSIIntClear(SSI0_BASE , SSI_RXTO | SSI_RXOR);
    
/* SPI clock & congig */    
    SSIClockSourceSet(SSI0_BASE , SSI_CLOCK_SYSTEM);
    SSIConfigSetExpClk(SSI0_BASE , SysCtlClockGet() , SSI_FRF_MOTO_MODE_0 , SSI_MODE_MASTER , 1000000U , 8U);
    HWREG(SSI0_BASE + SSI_O_CR1) |= SSI_CR1_LBM;  /* enable loopback mode */
    SSIEnable(SSI0_BASE);
    
    uint8_t tx_byte = 0U;
    uint8_t rx_byte;
    uint32_t temp;
    while(1)
    {
        while(SSIBusy(SSI0_BASE));
        SSIDataPut(SSI0_BASE , (uint32_t)tx_byte);
        while(SSIBusy(SSI0_BASE));
        SSIDataGet(SSI0_BASE , &temp);
        rx_byte = (uint8_t)temp;
        if(rx_byte)
        {
        }
        tx_byte++;
        
    }