diff options
| author | Kartik Rajput <kkartik@nvidia.com> | 2026-02-25 12:29:12 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-12 15:06:39 +0100 |
| commit | 87df45b4a83f13952958e9916af1b2dd56d4cfc7 (patch) | |
| tree | ce5c600c9c51634e63d23739d54c6cd713f89913 /drivers | |
| parent | 42157639ddc797053e0f16e6fe0f6b64034fe559 (diff) | |
serial: amba-pl011: Introduce set_uartclk_rate vendor flag
The NVIDIA Tegra264 UART relies on configuring the UART clock rate
directly to program the desired baud rate.
Introduce the set_uartclk_rate vendor flag. When set, the driver
uses clk_set_rate() to program the UART clock to the desired baud
rate and clk_round_rate() to determine the maximum supported baud
rate.
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Link: https://patch.msgid.link/20260225065915.341522-3-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index b6d881eb87cc..e12facb2a16a 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -115,6 +115,7 @@ struct vendor_data { bool always_enabled; bool fixed_options; bool skip_ibrd_fbrd; + bool set_uartclk_rate; unsigned int (*get_fifosize)(struct amba_device *dev); }; @@ -2096,6 +2097,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, unsigned int lcr_h, old_cr; unsigned long flags; unsigned int baud, quot, clkdiv; + unsigned int max_baud; unsigned int bits; if (uap->vendor->oversampling) @@ -2103,11 +2105,34 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, else clkdiv = 16; + max_baud = port->uartclk / clkdiv; + + if (uap->vendor->set_uartclk_rate) { + long max_clkrate = clk_round_rate(uap->clk, UINT_MAX); + + /* + * Clock is reprogrammable - determine max baud from the clock's + * maximum rate, not the current uartclk. + */ + if (max_clkrate > 0) + max_baud = max_clkrate / clkdiv; + } + /* * Ask the core to calculate the divisor for us. */ - baud = uart_get_baud_rate(port, termios, old, 0, - port->uartclk / clkdiv); + baud = uart_get_baud_rate(port, termios, old, 0, max_baud); + + if (uap->vendor->set_uartclk_rate) { + int err; + + err = clk_set_rate(uap->clk, baud * clkdiv); + if (err) { + dev_err(port->dev, "Failed to set clock rate: %d\n", err); + return; + } + } + #ifdef CONFIG_DMA_ENGINE /* * Adjust RX DMA polling rate with baud rate if not specified. |