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NVIDIA: SAUCE: tty/serial: tegra-utc: Add support for polling

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Add support for polling mode for the platforms that does not support
interrupts.

http://nvbugs/4409612
http://nvbugs/4341921

Signed-off-by: Kartik <kkartik@nvidia.com>
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by: Noah Wager <noah.wager@canonical.com>
Acked-by: Jacob Martin <jacob.martin@canonical.com>
Signed-off-by: Noah Wager <noah.wager@canonical.com>
This commit is contained in:
Kartik
2024-04-03 06:28:57 +00:00
committed by Noah Wager
parent 16fceb13b1
commit 6bdd71e372
1 changed files with 104 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/tty/serial/tegra-utc.c
+104 -22
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@@ -62,6 +62,10 @@ struct tegra_utc_port {
bool tx_enabled;
bool rx_enabled;
bool polling_enabled;
struct task_struct *rx_thread;
struct work_struct rx_poll_stop;
};
static struct tegra_utc_port *utc_ports[UART_NR];
@@ -149,13 +153,25 @@ static bool tegra_utc_tx_char(struct tegra_utc_port *tup, unsigned char c)
return true;
}
static void tegra_utc_tx_char_poll(struct tegra_utc_port *tup, unsigned char c)
{
while (tegra_utc_tx_readl(tup, TEGRA_UTC_FIFO_STATUS) & TEGRA_UTC_FIFO_FULL)
cpu_relax();
tegra_utc_tx_writel(c, tup, TEGRA_UTC_DATA);
}
static bool tegra_utc_tx_chars(struct tegra_utc_port *tup)
{
struct circ_buf *xmit = &tup->port.state->xmit;
if (tup->port.x_char) {
if (!tegra_utc_tx_char(tup, tup->port.x_char))
return true;
if (tup->polling_enabled) {
tegra_utc_tx_char_poll(tup, tup->port.x_char);
} else {
if (!tegra_utc_tx_char(tup, tup->port.x_char))
return true;
}
tup->port.x_char = 0;
}
@@ -166,8 +182,12 @@ static bool tegra_utc_tx_chars(struct tegra_utc_port *tup)
}
do {
if (!tegra_utc_tx_char(tup, xmit->buf[xmit->tail]))
break;
if (tup->polling_enabled) {
tegra_utc_tx_char_poll(tup, xmit->buf[xmit->tail]);
} else {
if (!tegra_utc_tx_char(tup, xmit->buf[xmit->tail]))
break;
}
uart_xmit_advance(&tup->port, 1);
} while (!uart_circ_empty(xmit));
@@ -266,8 +286,8 @@ static void tegra_utc_start_tx(struct uart_port *port)
{
struct tegra_utc_port *tup = container_of(port, struct tegra_utc_port, port);
if (tegra_utc_tx_chars(tup))
tegra_utc_set_tx_irq(tup, true);
if (tegra_utc_tx_chars(tup) && !tup->polling_enabled)
tegra_utc_set_tx_irq(tup, true);
}
static void tegra_utc_stop_rx(struct uart_port *port)
@@ -279,6 +299,9 @@ static void tegra_utc_stop_rx(struct uart_port *port)
tegra_utc_rx_writel(tup->rx_irqmask, tup, TEGRA_UTC_INTR_SET);
tup->rx_enabled = false;
if (tup->polling_enabled)
schedule_work(&tup->rx_poll_stop);
}
static void tegra_utc_hw_init(struct tegra_utc_port *tup)
@@ -290,17 +313,70 @@ static void tegra_utc_hw_init(struct tegra_utc_port *tup)
tegra_utc_reset_rx(tup);
}
static int tegra_utc_rx_poll_thread(void *data)
{
struct tegra_utc_port *tup = data;
unsigned int status;
dev_dbg(tup->port.dev, "Tegra-UTC RX poll thread initialized\n");
/* We are polling now disable interrupts. */
tup->rx_irqmask = 0x0;
tegra_utc_rx_writel(tup->rx_irqmask, tup, TEGRA_UTC_INTR_SET);
/* Continously poll FIFO status and read data if available. */
while (!kthread_should_stop()) {
status = tegra_utc_rx_readl(tup, TEGRA_UTC_FIFO_STATUS);
/* Wait for one character time and continue. */
if (status & TEGRA_UTC_FIFO_EMPTY) {
msleep(5);
continue;
}
spin_lock(&tup->port.lock);
tegra_utc_rx_chars(tup);
spin_unlock(&tup->port.lock);
}
return 0;
}
static void tegra_utc_stop_rx_poll_thread(struct work_struct *work)
{
struct tegra_utc_port *tup = container_of(work, struct tegra_utc_port, rx_poll_stop);
if (tup->rx_thread != NULL) {
kthread_stop(tup->rx_thread);
tup->rx_thread = NULL;
}
}
static int tegra_utc_startup(struct uart_port *port)
{
struct tegra_utc_port *tup = container_of(port, struct tegra_utc_port, port);
int ret;
tegra_utc_hw_init(tup);
ret = request_irq(tup->irq, tegra_utc_isr, 0, dev_name(port->dev), tup);
if (ret < 0) {
dev_err(port->dev, "failed to register interrupt handler\n");
return ret;
if (tup->polling_enabled) {
struct task_struct *rx_thread;
rx_thread = kthread_create(tegra_utc_rx_poll_thread, (void *) tup,
"tegra_utc_rx_poll_thread");
if (IS_ERR(rx_thread)) {
dev_err(port->dev, "unable to start rx poll thread\n");
return PTR_ERR(rx_thread);
}
tup->rx_thread = rx_thread;
wake_up_process(rx_thread);
} else {
int ret;
ret = request_irq(tup->irq, tegra_utc_isr, 0, dev_name(port->dev), tup);
if (ret < 0) {
dev_err(port->dev, "failed to register interrupt handler\n");
return ret;
}
}
return 0;
@@ -313,7 +389,8 @@ static void tegra_utc_shutdown(struct uart_port *port)
tegra_utc_rx_writel(0x0, tup, TEGRA_UTC_ENABLE);
tup->rx_enabled = false;
free_irq(tup->irq, tup);
if (!tup->polling_enabled)
free_irq(tup->irq, tup);
}
static void tegra_utc_set_termios(struct uart_port *port, struct ktermios *termios,
@@ -553,16 +630,6 @@ static int tegra_utc_probe(struct platform_device *pdev)
int ret;
int i;
if (pdev->dev.of_node) {
struct device_node *np = pdev->dev.of_node;
ret = of_property_read_u32(np, "current-speed", &baudrate);
if (ret)
return ret;
} else {
baudrate = 115200;
}
portnr = tegra_utc_find_free_port();
if (portnr < 0)
return portnr;
@@ -571,6 +638,21 @@ static int tegra_utc_probe(struct platform_device *pdev)
if (!tup)
return -ENOMEM;
if (pdev->dev.of_node) {
struct device_node *np = pdev->dev.of_node;
ret = of_property_read_u32(np, "current-speed", &baudrate);
if (ret)
return ret;
if (of_property_read_bool(np, "nvidia,utc-polling-enabled")) {
tup->polling_enabled = true;
INIT_WORK(&tup->rx_poll_stop, tegra_utc_stop_rx_poll_thread);
}
} else {
baudrate = 115200;
}
tup->irq = platform_get_irq(pdev, i);
if (tup->irq < 0) {
dev_err(&pdev->dev, "failed to get interrupts");