tty: serial: 8250: add DFL bus driver for Altera 16550.

Add a Device Feature List (DFL) bus driver for the Altera
16550 implementation of UART.

Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Marco Pagani <marpagan@redhat.com>
Link: https://lore.kernel.org/r/20230115151447.1353428-5-matthew.gerlach@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_dfl.c b/drivers/tty/serial/8250/8250_dfl.c
new file mode 100644 (file)
index 0000000..6c5ff01
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_dfl.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for FPGA UART
+ *
+ * Copyright (C) 2022 Intel Corporation.
+ *
+ * Authors:
+ *   Ananda Ravuri <ananda.ravuri@intel.com>
+ *   Matthew Gerlach <matthew.gerlach@linux.intel.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/dfl.h>
+#include <linux/errno.h>
+#include <linux/ioport.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/types.h>
+
+#include <linux/serial.h>
+#include <linux/serial_8250.h>
+
+#define DFHv1_PARAM_ID_CLK_FRQ    0x2
+#define DFHv1_PARAM_ID_FIFO_LEN   0x3
+
+#define DFHv1_PARAM_ID_REG_LAYOUT      0x4
+#define DFHv1_PARAM_REG_LAYOUT_WIDTH   GENMASK_ULL(63, 32)
+#define DFHv1_PARAM_REG_LAYOUT_SHIFT   GENMASK_ULL(31, 0)
+
+struct dfl_uart {
+       int line;
+};
+
+static int dfh_get_u64_param_val(struct dfl_device *dfl_dev, int param_id, u64 *pval)
+{
+       size_t psize;
+       u64 *p;
+
+       p = dfh_find_param(dfl_dev, param_id, &psize);
+       if (IS_ERR(p))
+               return PTR_ERR(p);
+
+       if (psize != sizeof(*pval))
+               return -EINVAL;
+
+       *pval = *p;
+
+       return 0;
+}
+
+static int dfl_uart_get_params(struct dfl_device *dfl_dev, struct uart_8250_port *uart)
+{
+       struct device *dev = &dfl_dev->dev;
+       u64 fifo_len, clk_freq, reg_layout;
+       u32 reg_width;
+       int ret;
+
+       ret = dfh_get_u64_param_val(dfl_dev, DFHv1_PARAM_ID_CLK_FRQ, &clk_freq);
+       if (ret)
+               return dev_err_probe(dev, ret, "missing CLK_FRQ param\n");
+
+       uart->port.uartclk = clk_freq;
+
+       ret = dfh_get_u64_param_val(dfl_dev, DFHv1_PARAM_ID_FIFO_LEN, &fifo_len);
+       if (ret)
+               return dev_err_probe(dev, ret, "missing FIFO_LEN param\n");
+
+       switch (fifo_len) {
+       case 32:
+               uart->port.type = PORT_ALTR_16550_F32;
+               break;
+
+       case 64:
+               uart->port.type = PORT_ALTR_16550_F64;
+               break;
+
+       case 128:
+               uart->port.type = PORT_ALTR_16550_F128;
+               break;
+
+       default:
+               return dev_err_probe(dev, -EINVAL, "unsupported FIFO_LEN %llu\n", fifo_len);
+       }
+
+       ret = dfh_get_u64_param_val(dfl_dev, DFHv1_PARAM_ID_REG_LAYOUT, &reg_layout);
+       if (ret)
+               return dev_err_probe(dev, ret, "missing REG_LAYOUT param\n");
+
+       uart->port.regshift = FIELD_GET(DFHv1_PARAM_REG_LAYOUT_SHIFT, reg_layout);
+       reg_width = FIELD_GET(DFHv1_PARAM_REG_LAYOUT_WIDTH, reg_layout);
+       switch (reg_width) {
+       case 4:
+               uart->port.iotype = UPIO_MEM32;
+               break;
+
+       case 2:
+               uart->port.iotype = UPIO_MEM16;
+               break;
+
+       default:
+               return dev_err_probe(dev, -EINVAL, "unsupported reg-width %u\n", reg_width);
+
+       }
+
+       return 0;
+}
+
+static int dfl_uart_probe(struct dfl_device *dfl_dev)
+{
+       struct device *dev = &dfl_dev->dev;
+       struct uart_8250_port uart = { };
+       struct dfl_uart *dfluart;
+       int ret;
+
+       uart.port.flags = UPF_IOREMAP;
+       uart.port.mapbase = dfl_dev->mmio_res.start;
+       uart.port.mapsize = resource_size(&dfl_dev->mmio_res);
+
+       ret = dfl_uart_get_params(dfl_dev, &uart);
+       if (ret < 0)
+               return dev_err_probe(dev, ret, "failed uart feature walk\n");
+
+       if (dfl_dev->num_irqs == 1)
+               uart.port.irq = dfl_dev->irqs[0];
+
+       dfluart = devm_kzalloc(dev, sizeof(*dfluart), GFP_KERNEL);
+       if (!dfluart)
+               return -ENOMEM;
+
+       dfluart->line = serial8250_register_8250_port(&uart);
+       if (dfluart->line < 0)
+               return dev_err_probe(dev, dfluart->line, "unable to register 8250 port.\n");
+
+       dev_set_drvdata(dev, dfluart);
+
+       return 0;
+}
+
+static void dfl_uart_remove(struct dfl_device *dfl_dev)
+{
+       struct dfl_uart *dfluart = dev_get_drvdata(&dfl_dev->dev);
+
+       serial8250_unregister_port(dfluart->line);
+}
+
+#define FME_FEATURE_ID_UART 0x24
+
+static const struct dfl_device_id dfl_uart_ids[] = {
+       { FME_ID, FME_FEATURE_ID_UART },
+       { }
+};
+MODULE_DEVICE_TABLE(dfl, dfl_uart_ids);
+
+static struct dfl_driver dfl_uart_driver = {
+       .drv = {
+               .name = "dfl-uart",
+       },
+       .id_table = dfl_uart_ids,
+       .probe = dfl_uart_probe,
+       .remove = dfl_uart_remove,
+};
+module_dfl_driver(dfl_uart_driver);
+
+MODULE_DESCRIPTION("DFL Intel UART driver");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL");

diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index b0f6234..020ef53 100644 (file)
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -370,6 +370,18 @@ config SERIAL_8250_FSL
          erratum for Freescale 16550 UARTs in the 8250 driver. It also
          enables support for ACPI enumeration.
 
+config SERIAL_8250_DFL
+       tristate "DFL bus driver for Altera 16550 UART"
+       depends on SERIAL_8250 && FPGA_DFL
+       help
+         This option enables support for a Device Feature List (DFL) bus
+         driver for the Altera 16550 UART. One or more Altera 16550 UARTs
+         can be instantiated in a FPGA and then be discovered during
+         enumeration of the DFL bus.
+
+         To compile this driver as a module, chose M here: the
+         module will be called 8250_dfl.
+
 config SERIAL_8250_DW
        tristate "Support for Synopsys DesignWare 8250 quirks"
        depends on SERIAL_8250

diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 1615bfd..4e1a328 100644 (file)
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554)       += 8250_exar_st16c554.o
 obj-$(CONFIG_SERIAL_8250_HUB6)         += 8250_hub6.o
 obj-$(CONFIG_SERIAL_8250_FSL)          += 8250_fsl.o
 obj-$(CONFIG_SERIAL_8250_MEN_MCB)      += 8250_men_mcb.o
+obj-$(CONFIG_SERIAL_8250_DFL)          += 8250_dfl.o
 obj-$(CONFIG_SERIAL_8250_DW)           += 8250_dw.o
 obj-$(CONFIG_SERIAL_8250_EM)           += 8250_em.o
 obj-$(CONFIG_SERIAL_8250_IOC3)         += 8250_ioc3.o