[PATCH v8 tty-next 2/4] serial: 8250_pci1xxxx: Add driver for quad-uart support

From: Kumaravel Thiagarajan
Date: Sat Dec 10 2022 - 08:13:17 EST

pci1xxxx is a PCIe switch with a multi-function endpoint on one of
its downstream ports. Quad-uart is one of the functions in the
multi-function endpoint. This driver loads for the quad-uart and
enumerates single or multiple instances of uart based on the PCIe
subsystem device ID.

Co-developed-by: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@xxxxxxxxxxxxx>
---
Changes in v8:
- Requested only required number of interrupt vectors in pci_alloc_irq_vectors
API based on sub-device id

Changes in v7:
- Used appropriate error codes
- Moved logical_to_physical_port_idx array to a function

Changes in v6:
- Removed un-necessary paranthesis
- Used array and removed switch cases to reduce complexity
- Handled failure case of pcim_iomap

Changes in v5:
- Used tabs instead of spaces in MACRO definitions for readability
- Removed assignments that are not required
- Removed redundant blank lines

Changes in v4:
- Renamed pci_setup_port to serial8250_pci_setup_port
- Added Copyright information to 8250_pcilib.c

Changes in v3:
- Used NSEC_PER_SEC, HZ_PER_MHZ, FIELD_PREP, FIELD_GET MACROs wherever
necessary
- Handled failure case of serial8250_register_8250_port properly
- Moved pci_setup_port to 8250_pcilib.c

Changes in v2:
- Use only the 62.5 MHz for baud clock.
- Define custom implementation for get_divisor and set_divisor.
- Use BOTHER instead of UPF_SPD_CUST for non standard baud rates
(untested).
- Correct indentation in clock divisor computation.
- Remove unnecessary call to pci_save_state in probe function.
- Fix null pointer dereference in probe function.
- Move pci1xxxx_rs485_config to a separate patch.
- Depends on SERIAL_8250_PCI & default to SERIAL_8250.
- Change PORT_MCHP16550A to 100 from 124.
---
MAINTAINERS | 7 +
drivers/tty/serial/8250/8250_pci1xxxx.c | 337 ++++++++++++++++++++++++
drivers/tty/serial/8250/8250_port.c | 8 +
drivers/tty/serial/8250/Kconfig | 11 +
drivers/tty/serial/8250/Makefile | 1 +
include/uapi/linux/serial_core.h | 3 +
6 files changed, 367 insertions(+)
create mode 100644 drivers/tty/serial/8250/8250_pci1xxxx.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d30f26e07cd3..aa98deaba249 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13434,6 +13434,13 @@ F: Documentation/devicetree/bindings/nvmem/microchip,sama7g5-otpc.yaml
F: drivers/nvmem/microchip-otpc.c
F: include/dt-bindings/nvmem/microchip,sama7g5-otpc.h

+MICROCHIP PCIe UART DRIVER
+M: Kumaravel Thiagarajan <kumaravel.thiagarajan@xxxxxxxxxxxxx>
+M: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
+L: linux-serial@xxxxxxxxxxxxxxx
+S: Maintained
+F: drivers/tty/serial/8250/8250_pci1xxxx.c
+
MICROCHIP PWM DRIVER
M: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
L: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated for non-subscribers)
diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
new file mode 100644
index 000000000000..05d1bd386f07
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
@@ -0,0 +1,337 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Probe module for 8250/16550-type MCHP PCI serial ports.
+ *
+ * Based on drivers/tty/serial/8250/8250_pci.c,
+ *
+ * Copyright (C) 2022 Microchip Technology Inc., All Rights Reserved.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/serial_core.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/units.h>
+#include <linux/tty.h>
+
+#include <asm/byteorder.h>
+
+#include "8250.h"
+#include "8250_pcilib.h"
+
+#define PCI_DEVICE_ID_EFAR_PCI12000 0xa002
+#define PCI_DEVICE_ID_EFAR_PCI11010 0xa012
+#define PCI_DEVICE_ID_EFAR_PCI11101 0xa022
+#define PCI_DEVICE_ID_EFAR_PCI11400 0xa032
+#define PCI_DEVICE_ID_EFAR_PCI11414 0xa042
+
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_4p 0x0001
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p012 0x0002
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p013 0x0003
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p023 0x0004
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p123 0x0005
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p01 0x0006
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p02 0x0007
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p03 0x0008
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p12 0x0009
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p13 0x000a
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p23 0x000b
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p0 0x000c
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p1 0x000d
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p2 0x000e
+#define PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p3 0x000f
+
+#define PCI_SUBDEVICE_ID_EFAR_PCI12000 PCI_DEVICE_ID_EFAR_PCI12000
+#define PCI_SUBDEVICE_ID_EFAR_PCI11010 PCI_DEVICE_ID_EFAR_PCI11010
+#define PCI_SUBDEVICE_ID_EFAR_PCI11101 PCI_DEVICE_ID_EFAR_PCI11101
+#define PCI_SUBDEVICE_ID_EFAR_PCI11400 PCI_DEVICE_ID_EFAR_PCI11400
+#define PCI_SUBDEVICE_ID_EFAR_PCI11414 PCI_DEVICE_ID_EFAR_PCI11414
+
+#define UART_ACTV_REG 0x11
+#define UART_BLOCK_SET_ACTIVE BIT(0)
+
+#define UART_PCI_CTRL_REG 0x80
+#define UART_PCI_CTRL_SET_MULTIPLE_MSI BIT(4)
+#define UART_PCI_CTRL_D3_CLK_ENABLE BIT(0)
+
+#define ADCL_CFG_REG 0x40
+#define ADCL_CFG_POL_SEL BIT(2)
+#define ADCL_CFG_PIN_SEL BIT(1)
+#define ADCL_CFG_EN BIT(0)
+
+#define UART_BIT_SAMPLE_CNT 16
+#define BAUD_CLOCK_DIV_INT_MSK GENMASK(31, 8)
+#define ADCL_CFG_RTS_DELAY_MASK GENMASK(11, 8)
+#define UART_CLOCK_DEFAULT (62500 * HZ_PER_KHZ)
+
+#define UART_WAKE_REG 0x8C
+#define UART_WAKE_MASK_REG 0x90
+#define UART_WAKE_N_PIN BIT(2)
+#define UART_WAKE_NCTS BIT(1)
+#define UART_WAKE_INT BIT(0)
+#define UART_WAKE_SRCS \
+ (UART_WAKE_N_PIN | UART_WAKE_NCTS | UART_WAKE_INT)
+
+#define UART_BAUD_CLK_DIVISOR_REG 0x54
+
+#define UART_RESET_REG 0x94
+#define UART_RESET_D3_RESET_DISABLE BIT(16)
+
+#define MAX_PORTS 4
+
+struct pci1xxxx_8250 {
+ struct pci_dev *pdev;
+ unsigned int nr;
+ void __iomem *membase;
+ int line[];
+};
+
+static int pci1xxxx_get_num_ports(struct pci_dev *dev)
+{
+ switch (dev->subsystem_device) {
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p0:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p1:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p2:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p3:
+ case PCI_SUBDEVICE_ID_EFAR_PCI12000:
+ case PCI_SUBDEVICE_ID_EFAR_PCI11010:
+ case PCI_SUBDEVICE_ID_EFAR_PCI11101:
+ case PCI_SUBDEVICE_ID_EFAR_PCI11400:
+ default:
+ return 1;
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p01:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p02:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p03:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p12:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p13:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_2p23:
+ return 2;
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p012:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p123:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p013:
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_3p023:
+ return 3;
+ case PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_4p:
+ case PCI_SUBDEVICE_ID_EFAR_PCI11414:
+ return 4;
+ }
+}
+
+static unsigned int pci1xxxx_get_divisor(struct uart_port *port,
+ unsigned int baud, unsigned int *frac)
+{
+ unsigned int quot;
+
+ /*
+ * Calculate baud rate sampling period in nanoseconds.
+ * Fractional part x denotes x/255 parts of a nanosecond.
+ */
+ quot = NSEC_PER_SEC / (baud * UART_BIT_SAMPLE_CNT);
+ *frac = (NSEC_PER_SEC - quot * baud * UART_BIT_SAMPLE_CNT) *
+ 255 / UART_BIT_SAMPLE_CNT / baud;
+
+ return quot;
+}
+
+static void pci1xxxx_set_divisor(struct uart_port *port, unsigned int baud,
+ unsigned int quot, unsigned int frac)
+{
+ writel(FIELD_PREP(BAUD_CLOCK_DIV_INT_MSK, quot) | frac,
+ port->membase + UART_BAUD_CLK_DIVISOR_REG);
+}
+
+static int pci1xxxx_setup(struct pci1xxxx_8250 *priv,
+ struct uart_8250_port *port, int port_idx)
+{
+ int ret;
+
+ port->port.flags |= UPF_FIXED_TYPE | UPF_SKIP_TEST;
+ port->port.type = PORT_MCHP16550A;
+ port->port.set_termios = serial8250_do_set_termios;
+ port->port.get_divisor = pci1xxxx_get_divisor;
+ port->port.set_divisor = pci1xxxx_set_divisor;
+
+ ret = serial8250_pci_setup_port(priv->pdev, port, 0, port_idx * 256, 0);
+ if (ret < 0)
+ return ret;
+
+ writeb(UART_BLOCK_SET_ACTIVE, port->port.membase + UART_ACTV_REG);
+ writeb(UART_WAKE_SRCS, port->port.membase + UART_WAKE_REG);
+ writeb(UART_WAKE_N_PIN, port->port.membase + UART_WAKE_MASK_REG);
+
+ return 0;
+}
+
+static int pci1xxxx_get_max_port(int subsys_dev)
+{
+ static int max_port[] = {
+ 1,/* PCI12000 PCI11010 PCI11101 PCI11400 */
+ 4,/* PCI4p */
+ 3,/* PCI3p012 */
+ 4,/* PCI3p013 */
+ 4,/* PCI3p023 */
+ 4,/* PCI3p123 */
+ 2,/* PCI2p01 */
+ 3,/* PCI2p02 */
+ 4,/* PCI2p03 */
+ 3,/* PCI2p12 */
+ 4,/* PCI2p13 */
+ 4,/* PCI2p23 */
+ 1,/* PCI1p0 */
+ 2,/* PCI1p1 */
+ 3,/* PCI1p2 */
+ 4,/* PCI1p3 */
+ };
+
+ if (subsys_dev > PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p3)
+ if (subsys_dev != PCI_SUBDEVICE_ID_EFAR_PCI11414)
+ return max_port[0];
+ else
+ return 4;
+ else
+ return max_port[subsys_dev];
+
+}
+
+static int pci1xxxx_logical_to_physical_port_translate(int subsys_dev, int port)
+{
+ static int logical_to_physical_port_idx[][MAX_PORTS] = {
+ {0, 1, 2, 3},/* PCI12000 PCI11010 PCI11101 PCI11400 PCI11414 */
+ {0, 1, 2, 3},/* PCI4p */
+ {0, 1, 2, -1},/* PCI3p012 */
+ {0, 1, 3, -1},/* PCI3p013 */
+ {0, 2, 3, -1},/* PCI3p023 */
+ {1, 2, 3, -1},/* PCI3p123 */
+ {0, 1, -1, -1},/* PCI2p01 */
+ {0, 2, -1, -1},/* PCI2p02 */
+ {0, 3, -1, -1},/* PCI2p03 */
+ {1, 2, -1, -1},/* PCI2p12 */
+ {1, 3, -1, -1},/* PCI2p13 */
+ {2, 3, -1, -1},/* PCI2p23 */
+ {0, -1, -1, -1},/* PCI1p0 */
+ {1, -1, -1, -1},/* PCI1p1 */
+ {2, -1, -1, -1},/* PCI1p2 */
+ {3, -1, -1, -1},/* PCI1p3 */
+ };
+
+ if (subsys_dev > PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p3)
+ return logical_to_physical_port_idx[0][port];
+ else
+ return logical_to_physical_port_idx[subsys_dev][port];
+}
+
+static int pci1xxxx_serial_probe(struct pci_dev *pdev,
+ const struct pci_device_id *id)
+{
+ struct device *dev = &pdev->dev;
+ struct pci1xxxx_8250 *priv;
+ struct uart_8250_port uart;
+ unsigned int nr_ports, i;
+ int max_vec_reqd;
+ int num_vectors;
+ int subsys_dev;
+ int port_idx;
+ int rc;
+
+ rc = pcim_enable_device(pdev);
+ if (rc)
+ return rc;
+
+ nr_ports = pci1xxxx_get_num_ports(pdev);
+
+ priv = devm_kzalloc(dev, struct_size(priv, line, nr_ports), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->membase = pcim_iomap(pdev, 0, 0);
+ if (!priv->membase)
+ return -ENOMEM;
+
+ priv->pdev = pdev;
+ subsys_dev = priv->pdev->subsystem_device;
+ priv->nr = nr_ports;
+ pci_set_master(pdev);
+ max_vec_reqd = pci1xxxx_get_max_port(subsys_dev);
+ num_vectors = pci_alloc_irq_vectors(pdev, 1, max_vec_reqd,
+ PCI_IRQ_ALL_TYPES);
+ if (num_vectors < 0)
+ return num_vectors;
+
+ memset(&uart, 0, sizeof(uart));
+ uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT;
+ uart.port.uartclk = UART_CLOCK_DEFAULT;
+ uart.port.dev = dev;
+
+ if (num_vectors == max_vec_reqd)
+ writeb(UART_PCI_CTRL_SET_MULTIPLE_MSI,
+ priv->membase + UART_PCI_CTRL_REG);
+
+ for (i = 0; i < nr_ports; i++)
+ priv->line[i] = -ENODEV;
+
+ for (i = 0; i < nr_ports; i++) {
+ port_idx = pci1xxxx_logical_to_physical_port_translate(subsys_dev, i);
+
+ if (num_vectors == max_vec_reqd)
+ uart.port.irq = pci_irq_vector(priv->pdev, port_idx);
+ else
+ uart.port.irq = pci_irq_vector(pdev, 0);
+
+ rc = pci1xxxx_setup(priv, &uart, port_idx);
+ if (rc) {
+ dev_warn(dev, "Failed to setup port %u\n", i);
+ continue;
+ }
+
+ priv->line[i] = serial8250_register_8250_port(&uart);
+ if (priv->line[i] < 0) {
+ dev_warn(dev,
+ "Couldn't register serial port %lx, irq %d, type %d, error %d\n",
+ uart.port.iobase, uart.port.irq, uart.port.iotype,
+ priv->line[i]);
+ }
+ }
+
+ pci_set_drvdata(pdev, priv);
+
+ return 0;
+}
+
+static void pci1xxxx_serial_remove(struct pci_dev *dev)
+{
+ struct pci1xxxx_8250 *priv = pci_get_drvdata(dev);
+ int i;
+
+ for (i = 0; i < priv->nr; i++) {
+ if (priv->line[i] >= 0)
+ serial8250_unregister_port(priv->line[i]);
+ }
+}
+
+static const struct pci_device_id pci1xxxx_pci_tbl[] = {
+ { PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI11010) },
+ { PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI11101) },
+ { PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI11400) },
+ { PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI11414) },
+ { PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_PCI12000) },
+ {}
+};
+MODULE_DEVICE_TABLE(pci, pci1xxxx_pci_tbl);
+
+static struct pci_driver pci1xxxx_pci_driver = {
+ .name = "pci1xxxx serial",
+ .probe = pci1xxxx_serial_probe,
+ .remove = pci1xxxx_serial_remove,
+ .id_table = pci1xxxx_pci_tbl,
+};
+module_pci_driver(pci1xxxx_pci_driver);
+
+MODULE_DESCRIPTION("Microchip Technology Inc. PCIe to UART module");
+MODULE_AUTHOR("Kumaravel Thiagarajan <kumaravel.thiagarajan@xxxxxxxxxxxxx>");
+MODULE_AUTHOR("Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 1d2a43214b48..ec2fe5fd7b02 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -313,6 +313,14 @@ static const struct serial8250_config uart_config[] = {
.rxtrig_bytes = {1, 4, 8, 14},
.flags = UART_CAP_FIFO,
},
+ [PORT_MCHP16550A] = {
+ .name = "MCHP16550A",
+ .fifo_size = 256,
+ .tx_loadsz = 256,
+ .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01,
+ .rxtrig_bytes = {2, 66, 130, 194},
+ .flags = UART_CAP_FIFO,
+ },
};

/* Uart divisor latch read */
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 768b73d5cb9a..588a73c0f4e8 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -295,6 +295,17 @@ config SERIAL_8250_HUB6
To compile this driver as a module, choose M here: the module
will be called 8250_hub6.

+config SERIAL_8250_PCI1XXXX
+ tristate "Microchip 8250 based serial port"
+ depends on SERIAL_8250 && PCI
+ select SERIAL_8250_PCILIB
+ default SERIAL_8250
+ help
+ Select this option if you have a setup with Microchip PCIe
+ Switch with serial port enabled and wish to enable 8250
+ serial driver for the serial interface. This driver support
+ will ensure to support baud rates upto 1.5Mpbs.
+
#
# Misc. options/drivers.
#
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index b9179d1f104b..98202fdf39f8 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_SERIAL_8250_ACCENT) += 8250_accent.o
obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o
obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554) += 8250_exar_st16c554.o
obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o
+obj-$(CONFIG_SERIAL_8250_PCI1XXXX) += 8250_pci1xxxx.o
obj-$(CONFIG_SERIAL_8250_FSL) += 8250_fsl.o
obj-$(CONFIG_SERIAL_8250_MEN_MCB) += 8250_men_mcb.o
obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 3ba34d8378bd..281fa286555c 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -207,6 +207,9 @@
/* Atheros AR933X SoC */
#define PORT_AR933X 99

+/* MCHP 16550A UART with 256 byte FIFOs */
+#define PORT_MCHP16550A 100
+
/* ARC (Synopsys) on-chip UART */
#define PORT_ARC 101

--
2.25.1