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serial: tegra: report clk rate errors

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Standard UART controllers support +/-4% baud rate error tolerance.
Tegra186 only supports 0% to +4% error tolerance whereas other Tegra
chips support standard +/-4% rate. Add chip data for knowing error
tolerance level for each soc. Creating new compatible for Tegra194
chip as it supports baud rate error tolerance of -2 to +2%, different
from older chips.

Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-12-git-send-email-kyarlagadda@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Krishna Yarlagadda 2019-09-04 10:13:06 +05:30 committed by Greg Kroah-Hartman
parent f04a3cc8d4
commit d781ec21ba
1 changed files with 57 additions and 2 deletions
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59
drivers/tty/serial/serial-tegra.c
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@ -89,6 +89,8 @@ struct tegra_uart_chip_data {
bool fifo_mode_enable_status;
int uart_max_port;
int max_dma_burst_bytes;
int error_tolerance_low_range;
int error_tolerance_high_range;
};
struct tegra_baud_tolerance {
@ -135,6 +137,8 @@ struct tegra_uart_port {
unsigned int rx_bytes_requested;
struct tegra_baud_tolerance *baud_tolerance;
int n_adjustable_baud_rates;
int required_rate;
int configured_rate;
};
static void tegra_uart_start_next_tx(struct tegra_uart_port *tup);
@ -350,6 +354,22 @@ static long tegra_get_tolerance_rate(struct tegra_uart_port *tup,
return rate;
}
static int tegra_check_rate_in_range(struct tegra_uart_port *tup)
{
long diff;
diff = ((long)(tup->configured_rate - tup->required_rate) * 10000)
/ tup->required_rate;
if (diff < (tup->cdata->error_tolerance_low_range * 100) ||
diff > (tup->cdata->error_tolerance_high_range * 100)) {
dev_err(tup->uport.dev,
"configured baud rate is out of range by %ld", diff);
return -EIO;
}
return 0;
}
static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
{
unsigned long rate;
@ -363,6 +383,8 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
if (tup->cdata->support_clk_src_div) {
rate = baud * 16;
tup->required_rate = rate;
if (tup->n_adjustable_baud_rates)
rate = tegra_get_tolerance_rate(tup, baud, rate);
@ -372,7 +394,11 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
"clk_set_rate() failed for rate %lu\n", rate);
return ret;
}
tup->configured_rate = clk_get_rate(tup->uart_clk);
divisor = 1;
ret = tegra_check_rate_in_range(tup);
if (ret < 0)
return ret;
} else {
rate = clk_get_rate(tup->uart_clk);
divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
@ -991,7 +1017,11 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
* enqueued
*/
tup->lcr_shadow = TEGRA_UART_DEFAULT_LSR;
tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
ret = tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
if (ret < 0) {
dev_err(tup->uport.dev, "Failed to set baud rate\n");
return ret;
}
tup->fcr_shadow |= UART_FCR_DMA_SELECT;
tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
@ -1190,6 +1220,7 @@ static void tegra_uart_set_termios(struct uart_port *u,
struct clk *parent_clk = clk_get_parent(tup->uart_clk);
unsigned long parent_clk_rate = clk_get_rate(parent_clk);
int max_divider = (tup->cdata->support_clk_src_div) ? 0x7FFF : 0xFFFF;
int ret;
max_divider *= 16;
spin_lock_irqsave(&u->lock, flags);
@ -1262,7 +1293,11 @@ static void tegra_uart_set_termios(struct uart_port *u,
parent_clk_rate/max_divider,
parent_clk_rate/16);
spin_unlock_irqrestore(&u->lock, flags);
tegra_set_baudrate(tup, baud);
ret = tegra_set_baudrate(tup, baud);
if (ret < 0) {
dev_err(tup->uport.dev, "Failed to set baud rate\n");
return;
}
if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud);
spin_lock_irqsave(&u->lock, flags);
@ -1399,6 +1434,8 @@ static struct tegra_uart_chip_data tegra20_uart_chip_data = {
.fifo_mode_enable_status = false,
.uart_max_port = 5,
.max_dma_burst_bytes = 4,
.error_tolerance_low_range = 0,
.error_tolerance_high_range = 4,
};
static struct tegra_uart_chip_data tegra30_uart_chip_data = {
@ -1408,6 +1445,8 @@ static struct tegra_uart_chip_data tegra30_uart_chip_data = {
.fifo_mode_enable_status = false,
.uart_max_port = 5,
.max_dma_burst_bytes = 4,
.error_tolerance_low_range = 0,
.error_tolerance_high_range = 4,
};
static struct tegra_uart_chip_data tegra186_uart_chip_data = {
@ -1417,6 +1456,19 @@ static struct tegra_uart_chip_data tegra186_uart_chip_data = {
.fifo_mode_enable_status = true,
.uart_max_port = 8,
.max_dma_burst_bytes = 8,
.error_tolerance_low_range = 0,
.error_tolerance_high_range = 4,
};
static struct tegra_uart_chip_data tegra194_uart_chip_data = {
.tx_fifo_full_status = true,
.allow_txfifo_reset_fifo_mode = false,
.support_clk_src_div = true,
.fifo_mode_enable_status = true,
.uart_max_port = 8,
.max_dma_burst_bytes = 8,
.error_tolerance_low_range = -2,
.error_tolerance_high_range = 2,
};
static const struct of_device_id tegra_uart_of_match[] = {
@ -1429,6 +1481,9 @@ static const struct of_device_id tegra_uart_of_match[] = {
}, {
.compatible = "nvidia,tegra186-hsuart",
.data = &tegra186_uart_chip_data,
}, {
.compatible = "nvidia,tegra194-hsuart",
.data = &tegra194_uart_chip_data,
}, {
},
};