Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, "Maciej W. Rozycki" <macro@orcam.me.uk>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.18 0999/1095] serial: 8250: Add proper clock handling for OxSemi PCIe devices
Date:   Mon, 15 Aug 2022 20:06:38 +0200
Message-Id: <20220815180510.450781260@linuxfoundation.org>
In-Reply-To: <20220815180429.240518113@linuxfoundation.org>
References: <20220815180429.240518113@linuxfoundation.org>
User-Agent: quilt/0.67
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Maciej W. Rozycki <macro@orcam.me.uk>

[ Upstream commit 366f6c955d4d1a5125ffcd6875ead26a3c7a2a1c ]

Oxford Semiconductor PCIe (Tornado) 950 serial port devices are driven
by a fixed 62.5MHz clock input derived from the 100MHz PCI Express clock.

We currently drive the device using its default oversampling rate of 16
and the clock prescaler disabled, consequently yielding the baud base of
3906250.  This base is inadequate for some of the high-speed baud rates
such as 460800bps, for which the closest rate possible can be obtained
by dividing the baud base by 8, yielding the baud rate of 488281.25bps,
which is off by 5.9638%.  This is enough for data communication to break
with the remote end talking actual 460800bps, where missed stop bits
have been observed.

We can do better however, by taking advantage of a reduced oversampling
rate, which can be set to any integer value from 4 to 16 inclusive by
programming the TCR register, and by using the clock prescaler, which
can be set to any value from 1 to 63.875 in increments of 0.125 in the
CPR/CPR2 register pair.  The prescaler has to be explicitly enabled
though by setting bit 7 in the MCR or otherwise it is bypassed (in the
enhanced mode that we enable) as if the value of 1 was used.

Make use of these features then as follows:

- Set the baud base to 15625000, reflecting the minimum oversampling
  rate of 4 with the clock prescaler and divisor both set to 1.

- Override the `set_mctrl' and set the MCR shadow there so as to have
  MCR[7] always set and have the 8250 core propagate these settings.

- Override the `get_divisor' handler and determine a good combination of
  parameters by using a lookup table with predetermined value pairs of
  the oversampling rate and the clock prescaler and finding a pair that
  divides the input clock such that the quotient, when rounded to the
  nearest integer, deviates the least from the exact result.  Calculate
  the clock divisor accordingly.

  Scale the resulting oversampling rate (only by powers of two) if
  possible so as to maximise it, reducing the divisor accordingly, and
  avoid a divisor overflow for very low baud rates by scaling the
  oversampling rate and/or the prescaler even if that causes some
  accuracy loss.

  Also handle the historic spd_cust feature so as to allow one to set
  all the three parameters manually to arbitrary values, by keeping the
  low 16 bits for the divisor and then putting TCR in bits 19:16 and
  CPR/CPR2 in bits 28:20, sanitising the bit pattern supplied such as
  to clamp CPR/CPR2 values between 0.000 and 0.875 inclusive to 33.875.
  This preserves compatibility with any existing setups, that is where
  requesting a custom divisor that only has any bits set among the low
  16 the oversampling rate of 16 and the clock prescaler of 33.875 will
  be used as with the original 8250.

  Finally abuse the `frac' argument to store the determined bit patterns
  for the TCR, CPR and CPR2 registers.

- Override the `set_divisor' handler so as to set the TCR, CPR and CPR2
  registers from the `frac' value supplied.  Set the divisor as usual.

With the baud base set to 15625000 and the unsigned 16-bit UART_DIV_MAX
limitation imposed by `serial8250_get_baud_rate' standard baud rates
below 300bps become unavailable in the regular way, e.g. the rate of
200bps requires the baud base to be divided by 78125 and that is beyond
the unsigned 16-bit range.  The historic spd_cust feature can still be
used to obtain such rates if so required.

See Documentation/tty/device_drivers/oxsemi-tornado.rst for more details.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181519450.9383@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 .../tty/device_drivers/oxsemi-tornado.rst     | 129 +++++++
 drivers/tty/serial/8250/8250_pci.c            | 339 ++++++++++++++----
 2 files changed, 400 insertions(+), 68 deletions(-)
 create mode 100644 Documentation/tty/device_drivers/oxsemi-tornado.rst

diff --git a/Documentation/tty/device_drivers/oxsemi-tornado.rst b/Documentation/tty/device_drivers/oxsemi-tornado.rst
new file mode 100644
index 000000000000..0180d8bb0881
--- /dev/null
+++ b/Documentation/tty/device_drivers/oxsemi-tornado.rst
@@ -0,0 +1,129 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================================================================
+Notes on Oxford Semiconductor PCIe (Tornado) 950 serial port devices
+====================================================================
+
+Oxford Semiconductor PCIe (Tornado) 950 serial port devices are driven
+by a fixed 62.5MHz clock input derived from the 100MHz PCI Express clock.
+
+The baud rate produced by the baud generator is obtained from this input
+frequency by dividing it by the clock prescaler, which can be set to any
+value from 1 to 63.875 in increments of 0.125, and then the usual 16-bit
+divisor is used as with the original 8250, to divide the frequency by a
+value from 1 to 65535.  Finally a programmable oversampling rate is used
+that can take any value from 4 to 16 to divide the frequency further and
+determine the actual baud rate used.  Baud rates from 15625000bps down
+to 0.933bps can be obtained this way.
+
+By default the oversampling rate is set to 16 and the clock prescaler is
+set to 33.875, meaning that the frequency to be used as the reference
+for the usual 16-bit divisor is 115313.653, which is close enough to the
+frequency of 115200 used by the original 8250 for the same values to be
+used for the divisor to obtain the requested baud rates by software that
+is unaware of the extra clock controls available.
+
+The oversampling rate is programmed with the TCR register and the clock
+prescaler is programmed with the CPR/CPR2 register pair[1][2][3][4].
+To switch away from the default value of 33.875 for the prescaler the
+the enhanced mode has to be explicitly enabled though, by setting bit 4
+of the EFR.  In that mode setting bit 7 in the MCR enables the prescaler
+or otherwise it is bypassed as if the value of 1 was used.  Additionally
+writing any value to CPR clears CPR2 for compatibility with old software
+written for older conventional PCI Oxford Semiconductor devices that do
+not have the extra prescaler's 9th bit in CPR2, so the CPR/CPR2 register
+pair has to be programmed in the right order.
+
+By using these parameters rates from 15625000bps down to 1bps can be
+obtained, with either exact or highly-accurate actual bit rates for
+standard and many non-standard rates.
+
+Here are the figures for the standard and some non-standard baud rates
+(including those quoted in Oxford Semiconductor documentation), giving
+the requested rate (r), the actual rate yielded (a) and its deviation
+from the requested rate (d), and the values of the oversampling rate
+(tcr), the clock prescaler (cpr) and the divisor (div) produced by the
+new `get_divisor' handler:
+
+r: 15625000, a: 15625000.00, d:  0.0000%, tcr:  4, cpr:  1.000, div:     1
+r: 12500000, a: 12500000.00, d:  0.0000%, tcr:  5, cpr:  1.000, div:     1
+r: 10416666, a: 10416666.67, d:  0.0000%, tcr:  6, cpr:  1.000, div:     1
+r:  8928571, a:  8928571.43, d:  0.0000%, tcr:  7, cpr:  1.000, div:     1
+r:  7812500, a:  7812500.00, d:  0.0000%, tcr:  8, cpr:  1.000, div:     1
+r:  4000000, a:  4000000.00, d:  0.0000%, tcr:  5, cpr:  3.125, div:     1
+r:  3686400, a:  3676470.59, d: -0.2694%, tcr:  8, cpr:  2.125, div:     1
+r:  3500000, a:  3496503.50, d: -0.0999%, tcr: 13, cpr:  1.375, div:     1
+r:  3000000, a:  2976190.48, d: -0.7937%, tcr: 14, cpr:  1.500, div:     1
+r:  2500000, a:  2500000.00, d:  0.0000%, tcr: 10, cpr:  2.500, div:     1
+r:  2000000, a:  2000000.00, d:  0.0000%, tcr: 10, cpr:  3.125, div:     1
+r:  1843200, a:  1838235.29, d: -0.2694%, tcr: 16, cpr:  2.125, div:     1
+r:  1500000, a:  1492537.31, d: -0.4975%, tcr:  5, cpr:  8.375, div:     1
+r:  1152000, a:  1152073.73, d:  0.0064%, tcr: 14, cpr:  3.875, div:     1
+r:   921600, a:   919117.65, d: -0.2694%, tcr: 16, cpr:  2.125, div:     2
+r:   576000, a:   576036.87, d:  0.0064%, tcr: 14, cpr:  3.875, div:     2
+r:   460800, a:   460829.49, d:  0.0064%, tcr:  7, cpr:  3.875, div:     5
+r:   230400, a:   230414.75, d:  0.0064%, tcr: 14, cpr:  3.875, div:     5
+r:   115200, a:   115207.37, d:  0.0064%, tcr: 14, cpr:  1.250, div:    31
+r:    57600, a:    57603.69, d:  0.0064%, tcr:  8, cpr:  3.875, div:    35
+r:    38400, a:    38402.46, d:  0.0064%, tcr: 14, cpr:  3.875, div:    30
+r:    19200, a:    19201.23, d:  0.0064%, tcr:  8, cpr:  3.875, div:   105
+r:     9600, a:     9600.06, d:  0.0006%, tcr:  9, cpr:  1.125, div:   643
+r:     4800, a:     4799.98, d: -0.0004%, tcr:  7, cpr:  2.875, div:   647
+r:     2400, a:     2400.02, d:  0.0008%, tcr:  9, cpr:  2.250, div:  1286
+r:     1200, a:     1200.00, d:  0.0000%, tcr: 14, cpr:  2.875, div:  1294
+r:      300, a:      300.00, d:  0.0000%, tcr: 11, cpr:  2.625, div:  7215
+r:      200, a:      200.00, d:  0.0000%, tcr: 16, cpr:  1.250, div: 15625
+r:      150, a:      150.00, d:  0.0000%, tcr: 13, cpr:  2.250, div: 14245
+r:      134, a:      134.00, d:  0.0000%, tcr: 11, cpr:  2.625, div: 16153
+r:      110, a:      110.00, d:  0.0000%, tcr: 12, cpr:  1.000, div: 47348
+r:       75, a:       75.00, d:  0.0000%, tcr:  4, cpr:  5.875, div: 35461
+r:       50, a:       50.00, d:  0.0000%, tcr: 16, cpr:  1.250, div: 62500
+r:       25, a:       25.00, d:  0.0000%, tcr: 16, cpr:  2.500, div: 62500
+r:        4, a:        4.00, d:  0.0000%, tcr: 16, cpr: 20.000, div: 48828
+r:        2, a:        2.00, d:  0.0000%, tcr: 16, cpr: 40.000, div: 48828
+r:        1, a:        1.00, d:  0.0000%, tcr: 16, cpr: 63.875, div: 61154
+
+With the baud base set to 15625000 and the unsigned 16-bit UART_DIV_MAX
+limitation imposed by `serial8250_get_baud_rate' standard baud rates
+below 300bps become unavailable in the regular way, e.g. the rate of
+200bps requires the baud base to be divided by 78125 and that is beyond
+the unsigned 16-bit range.  The historic spd_cust feature can still be
+used by encoding the values for, the prescaler, the oversampling rate
+and the clock divisor (DLM/DLL) as follows to obtain such rates if so
+required:
+
+ 31 29 28             20 19   16 15                            0
++-----+-----------------+-------+-------------------------------+
+|0 0 0|    CPR2:CPR     |  TCR  |            DLM:DLL            |
++-----+-----------------+-------+-------------------------------+
+
+Use a value such encoded for the `custom_divisor' field along with the
+ASYNC_SPD_CUST flag set in the `flags' field in `struct serial_struct'
+passed with the TIOCSSERIAL ioctl(2), such as with the setserial(8)
+utility and its `divisor' and `spd_cust' parameters, and the select
+the baud rate of 38400bps.  Note that the value of 0 in TCR sets the
+oversampling rate to 16 and prescaler values below 1 in CPR2/CPR are
+clamped by the driver to 1.
+
+For example the value of 0x1f4004e2 will set CPR2/CPR, TCR and DLM/DLL
+respectively to 0x1f4, 0x0 and 0x04e2, choosing the prescaler value,
+the oversampling rate and the clock divisor of 62.500, 16 and 1250
+respectively.  These parameters will set the baud rate for the serial
+port to 62500000 / 62.500 / 1250 / 16 = 50bps.
+
+References:
+
+[1] "OXPCIe200 PCI Express Multi-Port Bridge", Oxford Semiconductor,
+    Inc., DS-0045, 10 Nov 2008, Section "950 Mode", pp. 64-65
+
+[2] "OXPCIe952 PCI Express Bridge to Dual Serial & Parallel Port",
+    Oxford Semiconductor, Inc., DS-0046, Mar 06 08, Section "950 Mode",
+    p. 20
+
+[3] "OXPCIe954 PCI Express Bridge to Quad Serial Port", Oxford
+    Semiconductor, Inc., DS-0047, Feb 08, Section "950 Mode", p. 20
+
+[4] "OXPCIe958 PCI Express Bridge to Octal Serial Port", Oxford
+    Semiconductor, Inc., DS-0048, Feb 08, Section "950 Mode", p. 20
+
+Maciej W. Rozycki  <macro@orcam.me.uk>
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 4b0e84e01e55..818ed6cd3132 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -11,6 +11,7 @@
 #include <linux/pci.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/math.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/tty.h>
@@ -1044,6 +1045,208 @@ static int pci_oxsemi_tornado_init(struct pci_dev *dev)
 	return number_uarts;
 }
 
+/* Tornado-specific constants for the TCR and CPR registers; see below.  */
+#define OXSEMI_TORNADO_TCR_MASK	0xf
+#define OXSEMI_TORNADO_CPR_MASK	0x1ff
+#define OXSEMI_TORNADO_CPR_MIN	0x008
+#define OXSEMI_TORNADO_CPR_DEF	0x10f
+
+/*
+ * Determine the oversampling rate, the clock prescaler, and the clock
+ * divisor for the requested baud rate.  The clock rate is 62.5 MHz,
+ * which is four times the baud base, and the prescaler increments in
+ * steps of 1/8.  Therefore to make calculations on integers we need
+ * to use a scaled clock rate, which is the baud base multiplied by 32
+ * (or our assumed UART clock rate multiplied by 2).
+ *
+ * The allowed oversampling rates are from 4 up to 16 inclusive (values
+ * from 0 to 3 inclusive map to 16).  Likewise the clock prescaler allows
+ * values between 1.000 and 63.875 inclusive (operation for values from
+ * 0.000 to 0.875 has not been specified).  The clock divisor is the usual
+ * unsigned 16-bit integer.
+ *
+ * For the most accurate baud rate we use a table of predetermined
+ * oversampling rates and clock prescalers that records all possible
+ * products of the two parameters in the range from 4 up to 255 inclusive,
+ * and additionally 335 for the 1500000bps rate, with the prescaler scaled
+ * by 8.  The table is sorted by the decreasing value of the oversampling
+ * rate and ties are resolved by sorting by the decreasing value of the
+ * product.  This way preference is given to higher oversampling rates.
+ *
+ * We iterate over the table and choose the product of an oversampling
+ * rate and a clock prescaler that gives the lowest integer division
+ * result deviation, or if an exact integer divider is found we stop
+ * looking for it right away.  We do some fixup if the resulting clock
+ * divisor required would be out of its unsigned 16-bit integer range.
+ *
+ * Finally we abuse the supposed fractional part returned to encode the
+ * 4-bit value of the oversampling rate and the 9-bit value of the clock
+ * prescaler which will end up in the TCR and CPR/CPR2 registers.
+ */
+static unsigned int pci_oxsemi_tornado_get_divisor(struct uart_port *port,
+						   unsigned int baud,
+						   unsigned int *frac)
+{
+	static u8 p[][2] = {
+		{ 16, 14, }, { 16, 13, }, { 16, 12, }, { 16, 11, },
+		{ 16, 10, }, { 16,  9, }, { 16,  8, }, { 15, 17, },
+		{ 15, 16, }, { 15, 15, }, { 15, 14, }, { 15, 13, },
+		{ 15, 12, }, { 15, 11, }, { 15, 10, }, { 15,  9, },
+		{ 15,  8, }, { 14, 18, }, { 14, 17, }, { 14, 14, },
+		{ 14, 13, }, { 14, 12, }, { 14, 11, }, { 14, 10, },
+		{ 14,  9, }, { 14,  8, }, { 13, 19, }, { 13, 18, },
+		{ 13, 17, }, { 13, 13, }, { 13, 12, }, { 13, 11, },
+		{ 13, 10, }, { 13,  9, }, { 13,  8, }, { 12, 19, },
+		{ 12, 18, }, { 12, 17, }, { 12, 11, }, { 12,  9, },
+		{ 12,  8, }, { 11, 23, }, { 11, 22, }, { 11, 21, },
+		{ 11, 20, }, { 11, 19, }, { 11, 18, }, { 11, 17, },
+		{ 11, 11, }, { 11, 10, }, { 11,  9, }, { 11,  8, },
+		{ 10, 25, }, { 10, 23, }, { 10, 20, }, { 10, 19, },
+		{ 10, 17, }, { 10, 10, }, { 10,  9, }, { 10,  8, },
+		{  9, 27, }, {  9, 23, }, {  9, 21, }, {  9, 19, },
+		{  9, 18, }, {  9, 17, }, {  9,  9, }, {  9,  8, },
+		{  8, 31, }, {  8, 29, }, {  8, 23, }, {  8, 19, },
+		{  8, 17, }, {  8,  8, }, {  7, 35, }, {  7, 31, },
+		{  7, 29, }, {  7, 25, }, {  7, 23, }, {  7, 21, },
+		{  7, 19, }, {  7, 17, }, {  7, 15, }, {  7, 14, },
+		{  7, 13, }, {  7, 12, }, {  7, 11, }, {  7, 10, },
+		{  7,  9, }, {  7,  8, }, {  6, 41, }, {  6, 37, },
+		{  6, 31, }, {  6, 29, }, {  6, 23, }, {  6, 19, },
+		{  6, 17, }, {  6, 13, }, {  6, 11, }, {  6, 10, },
+		{  6,  9, }, {  6,  8, }, {  5, 67, }, {  5, 47, },
+		{  5, 43, }, {  5, 41, }, {  5, 37, }, {  5, 31, },
+		{  5, 29, }, {  5, 25, }, {  5, 23, }, {  5, 19, },
+		{  5, 17, }, {  5, 15, }, {  5, 13, }, {  5, 11, },
+		{  5, 10, }, {  5,  9, }, {  5,  8, }, {  4, 61, },
+		{  4, 59, }, {  4, 53, }, {  4, 47, }, {  4, 43, },
+		{  4, 41, }, {  4, 37, }, {  4, 31, }, {  4, 29, },
+		{  4, 23, }, {  4, 19, }, {  4, 17, }, {  4, 13, },
+		{  4,  9, }, {  4,  8, },
+	};
+	/* Scale the quotient for comparison to get the fractional part.  */
+	const unsigned int quot_scale = 65536;
+	unsigned int sclk = port->uartclk * 2;
+	unsigned int sdiv = DIV_ROUND_CLOSEST(sclk, baud);
+	unsigned int best_squot;
+	unsigned int squot;
+	unsigned int quot;
+	u16 cpr;
+	u8 tcr;
+	int i;
+
+	/* Old custom speed handling.  */
+	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST) {
+		unsigned int cust_div = port->custom_divisor;
+
+		quot = cust_div & UART_DIV_MAX;
+		tcr = (cust_div >> 16) & OXSEMI_TORNADO_TCR_MASK;
+		cpr = (cust_div >> 20) & OXSEMI_TORNADO_CPR_MASK;
+		if (cpr < OXSEMI_TORNADO_CPR_MIN)
+			cpr = OXSEMI_TORNADO_CPR_DEF;
+	} else {
+		best_squot = quot_scale;
+		for (i = 0; i < ARRAY_SIZE(p); i++) {
+			unsigned int spre;
+			unsigned int srem;
+			u8 cp;
+			u8 tc;
+
+			tc = p[i][0];
+			cp = p[i][1];
+			spre = tc * cp;
+
+			srem = sdiv % spre;
+			if (srem > spre / 2)
+				srem = spre - srem;
+			squot = DIV_ROUND_CLOSEST(srem * quot_scale, spre);
+
+			if (srem == 0) {
+				tcr = tc;
+				cpr = cp;
+				quot = sdiv / spre;
+				break;
+			} else if (squot < best_squot) {
+				best_squot = squot;
+				tcr = tc;
+				cpr = cp;
+				quot = DIV_ROUND_CLOSEST(sdiv, spre);
+			}
+		}
+		while (tcr <= (OXSEMI_TORNADO_TCR_MASK + 1) >> 1 &&
+		       quot % 2 == 0) {
+			quot >>= 1;
+			tcr <<= 1;
+		}
+		while (quot > UART_DIV_MAX) {
+			if (tcr <= (OXSEMI_TORNADO_TCR_MASK + 1) >> 1) {
+				quot >>= 1;
+				tcr <<= 1;
+			} else if (cpr <= OXSEMI_TORNADO_CPR_MASK >> 1) {
+				quot >>= 1;
+				cpr <<= 1;
+			} else {
+				quot = quot * cpr / OXSEMI_TORNADO_CPR_MASK;
+				cpr = OXSEMI_TORNADO_CPR_MASK;
+			}
+		}
+	}
+
+	*frac = (cpr << 8) | (tcr & OXSEMI_TORNADO_TCR_MASK);
+	return quot;
+}
+
+/*
+ * Set the oversampling rate in the transmitter clock cycle register (TCR),
+ * the clock prescaler in the clock prescaler register (CPR and CPR2), and
+ * the clock divisor in the divisor latch (DLL and DLM).  Note that for
+ * backwards compatibility any write to CPR clears CPR2 and therefore CPR
+ * has to be written first, followed by CPR2, which occupies the location
+ * of CKS used with earlier UART designs.
+ */
+static void pci_oxsemi_tornado_set_divisor(struct uart_port *port,
+					   unsigned int baud,
+					   unsigned int quot,
+					   unsigned int quot_frac)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
+	u8 cpr2 = quot_frac >> 16;
+	u8 cpr = quot_frac >> 8;
+	u8 tcr = quot_frac;
+
+	serial_icr_write(up, UART_TCR, tcr);
+	serial_icr_write(up, UART_CPR, cpr);
+	serial_icr_write(up, UART_CKS, cpr2);
+	serial8250_do_set_divisor(port, baud, quot, 0);
+}
+
+/*
+ * For Tornado devices we force MCR[7] set for the Divide-by-M N/8 baud rate
+ * generator prescaler (CPR and CPR2).  Otherwise no prescaler would be used.
+ */
+static void pci_oxsemi_tornado_set_mctrl(struct uart_port *port,
+					 unsigned int mctrl)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
+
+	up->mcr |= UART_MCR_CLKSEL;
+	serial8250_do_set_mctrl(port, mctrl);
+}
+
+static int pci_oxsemi_tornado_setup(struct serial_private *priv,
+				    const struct pciserial_board *board,
+				    struct uart_8250_port *up, int idx)
+{
+	struct pci_dev *dev = priv->dev;
+
+	if (pci_oxsemi_tornado_p(dev)) {
+		up->port.get_divisor = pci_oxsemi_tornado_get_divisor;
+		up->port.set_divisor = pci_oxsemi_tornado_set_divisor;
+		up->port.set_mctrl = pci_oxsemi_tornado_set_mctrl;
+	}
+
+	return pci_default_setup(priv, board, up, idx);
+}
+
 static int pci_asix_setup(struct serial_private *priv,
 		  const struct pciserial_board *board,
 		  struct uart_8250_port *port, int idx)
@@ -2245,7 +2448,7 @@ static struct pci_serial_quirk pci_serial_quirks[] = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.init		= pci_oxsemi_tornado_init,
-		.setup		= pci_default_setup,
+		.setup		= pci_oxsemi_tornado_setup,
 	},
 	{
 		.vendor		= PCI_VENDOR_ID_MAINPINE,
@@ -2253,7 +2456,7 @@ static struct pci_serial_quirk pci_serial_quirks[] = {
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.init		= pci_oxsemi_tornado_init,
-		.setup		= pci_default_setup,
+		.setup		= pci_oxsemi_tornado_setup,
 	},
 	{
 		.vendor		= PCI_VENDOR_ID_DIGI,
@@ -2261,7 +2464,7 @@ static struct pci_serial_quirk pci_serial_quirks[] = {
 		.subvendor		= PCI_SUBVENDOR_ID_IBM,
 		.subdevice		= PCI_ANY_ID,
 		.init			= pci_oxsemi_tornado_init,
-		.setup		= pci_default_setup,
+		.setup		= pci_oxsemi_tornado_setup,
 	},
 	{
 		.vendor         = PCI_VENDOR_ID_INTEL,
@@ -2578,7 +2781,7 @@ enum pci_board_num_t {
 	pbn_b0_2_1843200,
 	pbn_b0_4_1843200,
 
-	pbn_b0_1_3906250,
+	pbn_b0_1_15625000,
 
 	pbn_b0_bt_1_115200,
 	pbn_b0_bt_2_115200,
@@ -2657,10 +2860,10 @@ enum pci_board_num_t {
 	pbn_panacom4,
 	pbn_plx_romulus,
 	pbn_oxsemi,
-	pbn_oxsemi_1_3906250,
-	pbn_oxsemi_2_3906250,
-	pbn_oxsemi_4_3906250,
-	pbn_oxsemi_8_3906250,
+	pbn_oxsemi_1_15625000,
+	pbn_oxsemi_2_15625000,
+	pbn_oxsemi_4_15625000,
+	pbn_oxsemi_8_15625000,
 	pbn_intel_i960,
 	pbn_sgi_ioc3,
 	pbn_computone_4,
@@ -2803,10 +3006,10 @@ static struct pciserial_board pci_boards[] = {
 		.uart_offset	= 8,
 	},
 
-	[pbn_b0_1_3906250] = {
+	[pbn_b0_1_15625000] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 1,
-		.base_baud	= 3906250,
+		.base_baud	= 15625000,
 		.uart_offset	= 8,
 	},
 
@@ -3187,31 +3390,31 @@ static struct pciserial_board pci_boards[] = {
 		.base_baud	= 115200,
 		.uart_offset	= 8,
 	},
-	[pbn_oxsemi_1_3906250] = {
+	[pbn_oxsemi_1_15625000] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 1,
-		.base_baud	= 3906250,
+		.base_baud	= 15625000,
 		.uart_offset	= 0x200,
 		.first_offset	= 0x1000,
 	},
-	[pbn_oxsemi_2_3906250] = {
+	[pbn_oxsemi_2_15625000] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 2,
-		.base_baud	= 3906250,
+		.base_baud	= 15625000,
 		.uart_offset	= 0x200,
 		.first_offset	= 0x1000,
 	},
-	[pbn_oxsemi_4_3906250] = {
+	[pbn_oxsemi_4_15625000] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 4,
-		.base_baud	= 3906250,
+		.base_baud	= 15625000,
 		.uart_offset	= 0x200,
 		.first_offset	= 0x1000,
 	},
-	[pbn_oxsemi_8_3906250] = {
+	[pbn_oxsemi_8_15625000] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 8,
-		.base_baud	= 3906250,
+		.base_baud	= 15625000,
 		.uart_offset	= 0x200,
 		.first_offset	= 0x1000,
 	},
@@ -4192,165 +4395,165 @@ static const struct pci_device_id serial_pci_tbl[] = {
 	 */
 	{	PCI_VENDOR_ID_OXSEMI, 0xc101,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc105,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc11b,    /* OXPCIe952 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc11f,    /* OXPCIe952 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc120,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc124,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc138,    /* OXPCIe952 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc13d,    /* OXPCIe952 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc140,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc141,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc144,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc145,    /* OXPCIe952 1 Legacy UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_b0_1_3906250 },
+		pbn_b0_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc158,    /* OXPCIe952 2 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_2_3906250 },
+		pbn_oxsemi_2_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc15d,    /* OXPCIe952 2 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_2_3906250 },
+		pbn_oxsemi_2_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc208,    /* OXPCIe954 4 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_4_3906250 },
+		pbn_oxsemi_4_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc20d,    /* OXPCIe954 4 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_4_3906250 },
+		pbn_oxsemi_4_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc308,    /* OXPCIe958 8 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_8_3906250 },
+		pbn_oxsemi_8_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc30d,    /* OXPCIe958 8 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_8_3906250 },
+		pbn_oxsemi_8_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc40b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc40f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc41b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc41f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc42b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc42f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc43b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc43f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc44b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc44f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc45b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc45f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc46b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc46f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc47b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc47f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc48b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc48f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc49b,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc49f,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc4ab,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc4af,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc4bb,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc4bf,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc4cb,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_OXSEMI, 0xc4cf,    /* OXPCIe200 1 Native UART */
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	/*
 	 * Mainpine Inc. IQ Express "Rev3" utilizing OxSemi Tornado
 	 */
 	{	PCI_VENDOR_ID_MAINPINE, 0x4000,	/* IQ Express 1 Port V.34 Super-G3 Fax */
 		PCI_VENDOR_ID_MAINPINE, 0x4001, 0, 0,
-		pbn_oxsemi_1_3906250 },
+		pbn_oxsemi_1_15625000 },
 	{	PCI_VENDOR_ID_MAINPINE, 0x4000,	/* IQ Express 2 Port V.34 Super-G3 Fax */
 		PCI_VENDOR_ID_MAINPINE, 0x4002, 0, 0,
-		pbn_oxsemi_2_3906250 },
+		pbn_oxsemi_2_15625000 },
 	{	PCI_VENDOR_ID_MAINPINE, 0x4000,	/* IQ Express 4 Port V.34 Super-G3 Fax */
 		PCI_VENDOR_ID_MAINPINE, 0x4004, 0, 0,
-		pbn_oxsemi_4_3906250 },
+		pbn_oxsemi_4_15625000 },
 	{	PCI_VENDOR_ID_MAINPINE, 0x4000,	/* IQ Express 8 Port V.34 Super-G3 Fax */
 		PCI_VENDOR_ID_MAINPINE, 0x4008, 0, 0,
-		pbn_oxsemi_8_3906250 },
+		pbn_oxsemi_8_15625000 },
 
 	/*
 	 * Digi/IBM PCIe 2-port Async EIA-232 Adapter utilizing OxSemi Tornado
 	 */
 	{	PCI_VENDOR_ID_DIGI, PCIE_DEVICE_ID_NEO_2_OX_IBM,
 		PCI_SUBVENDOR_ID_IBM, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_2_3906250 },
+		pbn_oxsemi_2_15625000 },
 	/*
 	 * EndRun Technologies. PCI express device range.
 	 * EndRun PTP/1588 has 2 Native UARTs utilizing OxSemi 952.
 	 */
 	{	PCI_VENDOR_ID_ENDRUN, PCI_DEVICE_ID_ENDRUN_1588,
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_oxsemi_2_3906250 },
+		pbn_oxsemi_2_15625000 },
 
 	/*
 	 * SBS Technologies, Inc. P-Octal and PMC-OCTPRO cards,
-- 
2.35.1