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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /drivers/tty/tty_baudrate.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'drivers/tty/tty_baudrate.c')
-rw-r--r--drivers/tty/tty_baudrate.c215
1 files changed, 215 insertions, 0 deletions
diff --git a/drivers/tty/tty_baudrate.c b/drivers/tty/tty_baudrate.c
new file mode 100644
index 000000000..f9b49939c
--- /dev/null
+++ b/drivers/tty/tty_baudrate.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/termios.h>
+#include <linux/tty.h>
+#include <linux/export.h>
+#include "tty.h"
+
+
+/*
+ * Routine which returns the baud rate of the tty
+ *
+ * Note that the baud_table needs to be kept in sync with the
+ * include/asm/termbits.h file.
+ */
+static const speed_t baud_table[] = {
+ 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
+ 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
+#ifdef __sparc__
+ 76800, 153600, 307200, 614400, 921600, 500000, 576000,
+ 1000000, 1152000, 1500000, 2000000
+#else
+ 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
+ 2500000, 3000000, 3500000, 4000000
+#endif
+};
+
+static const tcflag_t baud_bits[] = {
+ B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400,
+ B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800,
+#ifdef __sparc__
+ B76800, B153600, B307200, B614400, B921600, B500000, B576000,
+ B1000000, B1152000, B1500000, B2000000
+#else
+ B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000,
+ B2500000, B3000000, B3500000, B4000000
+#endif
+};
+
+static int n_baud_table = ARRAY_SIZE(baud_table);
+
+/**
+ * tty_termios_baud_rate
+ * @termios: termios structure
+ *
+ * Convert termios baud rate data into a speed. This should be called
+ * with the termios lock held if this termios is a terminal termios
+ * structure. Device drivers can call this function but should use
+ * ->c_[io]speed directly as they are updated.
+ *
+ * Locking: none
+ */
+
+speed_t tty_termios_baud_rate(const struct ktermios *termios)
+{
+ unsigned int cbaud;
+
+ cbaud = termios->c_cflag & CBAUD;
+
+ /* Magic token for arbitrary speed via c_ispeed/c_ospeed */
+ if (cbaud == BOTHER)
+ return termios->c_ospeed;
+
+ if (cbaud & CBAUDEX) {
+ cbaud &= ~CBAUDEX;
+ cbaud += 15;
+ }
+ return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
+}
+EXPORT_SYMBOL(tty_termios_baud_rate);
+
+/**
+ * tty_termios_input_baud_rate
+ * @termios: termios structure
+ *
+ * Convert termios baud rate data into a speed. This should be called
+ * with the termios lock held if this termios is a terminal termios
+ * structure. Device drivers can call this function but should use
+ * ->c_[io]speed directly as they are updated.
+ *
+ * Locking: none
+ */
+
+speed_t tty_termios_input_baud_rate(const struct ktermios *termios)
+{
+ unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
+
+ if (cbaud == B0)
+ return tty_termios_baud_rate(termios);
+
+ /* Magic token for arbitrary speed via c_ispeed */
+ if (cbaud == BOTHER)
+ return termios->c_ispeed;
+
+ if (cbaud & CBAUDEX) {
+ cbaud &= ~CBAUDEX;
+ cbaud += 15;
+ }
+ return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
+}
+EXPORT_SYMBOL(tty_termios_input_baud_rate);
+
+/**
+ * tty_termios_encode_baud_rate
+ * @termios: ktermios structure holding user requested state
+ * @ibaud: input speed
+ * @obaud: output speed
+ *
+ * Encode the speeds set into the passed termios structure. This is
+ * used as a library helper for drivers so that they can report back
+ * the actual speed selected when it differs from the speed requested
+ *
+ * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
+ * we need to carefully set the bits when the user does not get the
+ * desired speed. We allow small margins and preserve as much of possible
+ * of the input intent to keep compatibility.
+ *
+ * Locking: Caller should hold termios lock. This is already held
+ * when calling this function from the driver termios handler.
+ *
+ * The ifdefs deal with platforms whose owners have yet to update them
+ * and will all go away once this is done.
+ */
+
+void tty_termios_encode_baud_rate(struct ktermios *termios,
+ speed_t ibaud, speed_t obaud)
+{
+ int i = 0;
+ int ifound = -1, ofound = -1;
+ int iclose = ibaud/50, oclose = obaud/50;
+ int ibinput = 0;
+
+ if (obaud == 0) /* CD dropped */
+ ibaud = 0; /* Clear ibaud to be sure */
+
+ termios->c_ispeed = ibaud;
+ termios->c_ospeed = obaud;
+
+ if (((termios->c_cflag >> IBSHIFT) & CBAUD) != B0)
+ ibinput = 1; /* An input speed was specified */
+
+ /* If the user asked for a precise weird speed give a precise weird
+ * answer. If they asked for a Bfoo speed they may have problems
+ * digesting non-exact replies so fuzz a bit.
+ */
+
+ if ((termios->c_cflag & CBAUD) == BOTHER) {
+ oclose = 0;
+ if (!ibinput)
+ iclose = 0;
+ }
+ if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
+ iclose = 0;
+
+ termios->c_cflag &= ~CBAUD;
+ termios->c_cflag &= ~(CBAUD << IBSHIFT);
+
+ /*
+ * Our goal is to find a close match to the standard baud rate
+ * returned. Walk the baud rate table and if we get a very close
+ * match then report back the speed as a POSIX Bxxxx value by
+ * preference
+ */
+
+ do {
+ if (obaud - oclose <= baud_table[i] &&
+ obaud + oclose >= baud_table[i]) {
+ termios->c_cflag |= baud_bits[i];
+ ofound = i;
+ }
+ if (ibaud - iclose <= baud_table[i] &&
+ ibaud + iclose >= baud_table[i]) {
+ /* For the case input == output don't set IBAUD bits
+ * if the user didn't do so.
+ */
+ if (ofound == i && !ibinput) {
+ ifound = i;
+ } else {
+ ifound = i;
+ termios->c_cflag |= (baud_bits[i] << IBSHIFT);
+ }
+ }
+ } while (++i < n_baud_table);
+
+ /* If we found no match then use BOTHER. */
+ if (ofound == -1)
+ termios->c_cflag |= BOTHER;
+ /* Set exact input bits only if the input and output differ or the
+ * user already did.
+ */
+ if (ifound == -1 && (ibaud != obaud || ibinput))
+ termios->c_cflag |= (BOTHER << IBSHIFT);
+}
+EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
+
+/**
+ * tty_encode_baud_rate - set baud rate of the tty
+ * @tty: terminal device
+ * @ibaud: input baud rate
+ * @obaud: output baud rate
+ *
+ * Update the current termios data for the tty with the new speed
+ * settings. The caller must hold the termios_rwsem for the tty in
+ * question.
+ */
+
+void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
+{
+ tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
+}
+EXPORT_SYMBOL_GPL(tty_encode_baud_rate);