/**
* xuartps_set_baud_rate - Calculate and set the baud rate
* @port: Handle to the uart port structure
* @baud: Baud rate to set
* Returns baud rate, requested baud when possible, or actual baud when there
* was too much error, zero if no valid divisors are found.
*/
static unsigned int xuartps_set_baud_rate(struct uart_port *port,
unsigned int baud)
{
unsigned int calc_baud;
u32 cd = 0, bdiv = 0;
u32 mreg;
int div8;
struct xuartps *xuartps = port->private_data;
calc_baud = xuartps_calc_baud_divs(port->uartclk, baud, &bdiv, &cd,
&div8);
/* Write new divisors to hardware */
mreg = xuartps_readl(XUARTPS_MR_OFFSET);
if (div8)
mreg |= XUARTPS_MR_CLKSEL;
else
mreg &= ~XUARTPS_MR_CLKSEL;
xuartps_writel(mreg, XUARTPS_MR_OFFSET);
xuartps_writel(cd, XUARTPS_BAUDGEN_OFFSET);
xuartps_writel(bdiv, XUARTPS_BAUDDIV_OFFSET);
xuartps->baud = baud;
return calc_baud;
}
/**
* xuartps_clk_notitifer_cb - Clock notifier callback
* @nb: Notifier block
* @event: Notify event
* @data: Notifier data
* Returns NOTIFY_OK on success, NOTIFY_BAD on error.
*/
static int xuartps_clk_notifier_cb(struct notifier_block *nb,
unsigned long event, void *data)
{
u32 ctrl_reg;
struct uart_port *port;
int locked = 0;
struct clk_notifier_data *ndata = data;
unsigned long flags = 0;
struct xuartps *xuartps = to_xuartps(nb);
port = xuartps->port;
if (port->suspended)
return NOTIFY_OK;
switch (event) {
case PRE_RATE_CHANGE:
{
u32 bdiv;
u32 cd;
int div8;
/*
* Find out if current baud-rate can be achieved with new clock
* frequency.
*/
if (!xuartps_calc_baud_divs(ndata->new_rate, xuartps->baud,
&bdiv, &cd, &div8))
return NOTIFY_BAD;
spin_lock_irqsave(&xuartps->port->lock, flags);
/* Disable the TX and RX to set baud rate */
xuartps_writel(xuartps_readl(XUARTPS_CR_OFFSET) |
(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS),
XUARTPS_CR_OFFSET);
spin_unlock_irqrestore(&xuartps->port->lock, flags);
return NOTIFY_OK;
}
case POST_RATE_CHANGE:
/*
* Set clk dividers to generate correct baud with new clock
* frequency.
*/
spin_lock_irqsave(&xuartps->port->lock, flags);
locked = 1;
port->uartclk = ndata->new_rate;
xuartps->baud = xuartps_set_baud_rate(xuartps->port,
xuartps->baud);
/* fall through */
case ABORT_RATE_CHANGE:
if (!locked)
spin_lock_irqsave(&xuartps->port->lock, flags);
/* Set TX/RX Reset */
xuartps_writel(xuartps_readl(XUARTPS_CR_OFFSET) |
(XUARTPS_CR_TXRST | XUARTPS_CR_RXRST),
XUARTPS_CR_OFFSET);
while (xuartps_readl(XUARTPS_CR_OFFSET) &
(XUARTPS_CR_TXRST | XUARTPS_CR_RXRST))
cpu_relax();
/*
* Clear the RX disable and TX disable bits and then set the TX
* enable bit and RX enable bit to enable the transmitter and
* receiver.
*/
xuartps_writel(rx_timeout, XUARTPS_RXTOUT_OFFSET);
ctrl_reg = xuartps_readl(XUARTPS_CR_OFFSET);
xuartps_writel(
(ctrl_reg & ~(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS)) |
(XUARTPS_CR_TX_EN | XUARTPS_CR_RX_EN),
XUARTPS_CR_OFFSET);
spin_unlock_irqrestore(&xuartps->port->lock, flags);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
/*
* no clue yet how to implement this. i think we need access to the port
* structure in this function to do the required changes. but i don't know how
* to get it in here.
*
* Think I got it. port must have a notifier_block* member from where we then
* can get to the outer port structure with a container_of() call.
*
* Not sure when to stop UART. probably it's enough to stop, reconfigure, start
* in POST_RATE_CHANGE
*/
static int xuartps_clk_notifier_cb(struct notifier_block *nb,
unsigned long event, void *data)
{
struct clk_notifier_data *ndata = data;
struct uart_port *port;
struct xuartps *xuartps = to_xuartps(nb);
port = xuartps->port;
switch (event) {
case PRE_RATE_CHANGE:
{
u32 bdiv;
u32 cd;
int div8;
/* Find out if current baud-rate can be achieved with new clock
* frequency. */
if (!xuartps_calc_baud_divs(ndata->new_rate, xuartps->baud,
&bdiv, &cd, &div8))
return NOTIFY_BAD;
return NOTIFY_OK;
}
case POST_RATE_CHANGE:
/* Set clk dividers to generate correct baud with new clock
* frequency. */
{
u32 ctrl_reg;
unsigned long flags = 0;
spin_lock_irqsave(&xuartps->port->lock, flags);
port->uartclk = ndata->new_rate;
/* Empty the receive FIFO 1st before making changes */
while ((xuartps_readl(XUARTPS_SR_OFFSET) &
XUARTPS_SR_RXEMPTY) != XUARTPS_SR_RXEMPTY)
xuartps_readl(XUARTPS_FIFO_OFFSET);
/* Disable the TX and RX to set baud rate */
xuartps_writel(xuartps_readl(XUARTPS_CR_OFFSET) |
(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS),
XUARTPS_CR_OFFSET);
xuartps->baud = xuartps_set_baud_rate(xuartps->port,
xuartps->baud);
/* Set TX/RX Reset */
xuartps_writel(xuartps_readl(XUARTPS_CR_OFFSET) |
(XUARTPS_CR_TXRST | XUARTPS_CR_RXRST),
XUARTPS_CR_OFFSET);
/*
* Clear the RX disable and TX disable bits and then set the TX
* enable bit and RX enable bit to enable the transmitter and
* receiver.
*/
ctrl_reg = xuartps_readl(XUARTPS_CR_OFFSET);
xuartps_writel(
(ctrl_reg & ~(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS)) |
(XUARTPS_CR_TX_EN | XUARTPS_CR_RX_EN),
XUARTPS_CR_OFFSET);
spin_unlock_irqrestore(&xuartps->port->lock, flags);
return NOTIFY_OK;
}
case ABORT_RATE_CHANGE:
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}