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SubjectRe: [PATCH v6 tty-next 2/4] serial: 8250_pci1xxxx: Add driver for quad-uart support.
On Thu, 1 Dec 2022, Kumaravel Thiagarajan wrote:

> 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@microchip.com>
> Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
> Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
> ---
> 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 | 298 ++++++++++++++++++++++++
> 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, 328 insertions(+)
> create mode 100644 drivers/tty/serial/8250/8250_pci1xxxx.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index d30f26e07cd3..20c868776a5e 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@microchip.com>
> +M: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
> +L: linux-serial@vger.kernel.org
> +S: Maintained
> +F: drivers/tty/serial/8250/8250_pci1xxxx.c
> +
> MICROCHIP PWM DRIVER
> M: Claudiu Beznea <claudiu.beznea@microchip.com>
> L: linux-arm-kernel@lists.infradead.org (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..d5037e76b636
> --- /dev/null
> +++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
> @@ -0,0 +1,298 @@
> +// 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 0xa002
> +#define PCI_SUBDEVICE_ID_EFAR_PCI11010 0xa012
> +#define PCI_SUBDEVICE_ID_EFAR_PCI11101 0xa022
> +#define PCI_SUBDEVICE_ID_EFAR_PCI11400 0xa032
> +#define PCI_SUBDEVICE_ID_EFAR_PCI11414 0xa042

Since those numbers seems to match the others, could you just do:

#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 (62.5 * HZ_PER_MHZ)

I don't think you want to go into float realm. Just do 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) /
> + UART_BIT_SAMPLE_CNT * 255 / baud;

Is it fine to div first before * 255 from precision point of view?

> +
> + 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_serial_probe(struct pci_dev *pdev,
> + const struct pci_device_id *id)
> +{
> + 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 */

Add comma also to the last item.

This array can go outside of function's scope.

> + };
> + struct device *dev = &pdev->dev;
> + struct pci1xxxx_8250 *priv;
> + struct uart_8250_port uart;
> + unsigned int nr_ports, i;
> + 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);
> +
> + num_vectors = pci_alloc_irq_vectors(pdev, 1, 4, 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 == 4)
> + writeb(UART_PCI_CTRL_SET_MULTIPLE_MSI,
> + priv->membase + UART_PCI_CTRL_REG);
> + else
> + uart.port.irq = pci_irq_vector(pdev, 0);
> +
> + for (i = 0; i < nr_ports; i++)
> + priv->line[i] = -ENOSPC;

-ENODEV might be more appropriate.

> +
> + for (i = 0; i < nr_ports; i++) {
> + if (subsys_dev > 0x0f)

> PCI_SUBDEVICE_ID_EFAR_PCI1XXXX_1p3

> + port_idx = logical_to_physical_port_idx[0][i];
> + else
> + port_idx = logical_to_physical_port_idx[subsys_dev][i];
> +
> + if (num_vectors == 4)
> + uart.port.irq = pci_irq_vector(priv->pdev, port_idx);
> +
> + 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@microchip.com>");
> +MODULE_AUTHOR("Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>");
> +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 3088eaff3ad0..f67542470eae 100644
> --- a/drivers/tty/serial/8250/Kconfig
> +++ b/drivers/tty/serial/8250/Kconfig
> @@ -292,6 +292,17 @@ 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

Do you actually need this any more after pcilib? It's not like all PCI
UARTs depends on SERIAL_8250_PCI. An alternative might be this:

depends on SERIAL_8250 && PCI


--
i.

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