[PATCH v8 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550.

From: matthew . gerlach
Date: Wed Dec 28 2022 - 13:16:44 EST

From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>

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

Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
v8: use dfh_get_u64_param_vals()

v7: no change

v6: move driver specific parameter definitions to limit scope

v5: removed unneeded blank line
removed unneeded includes
included device.h and types.h
removed unneeded local variable
remove calls to dev_dbg
memset -> { }
remove space after period
explicitly include used headers
remove redundant Inc from Copyright
fix format specifier

v4: use dev_err_probe() everywhere that is appropriate
clean up noise
change error messages to use the word, unsupported
tried again to sort Makefile and KConfig better
reorder probe function for easier error handling
use new dfh_find_param API

v3: use passed in location of registers
use cleaned up functions for parsing parameters

v2: clean up error messages
alphabetize header files
fix 'missing prototype' error by making function static
tried to sort Makefile and Kconfig better
---
drivers/tty/serial/8250/8250_dfl.c | 150 +++++++++++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 12 +++
drivers/tty/serial/8250/Makefile | 1 +
3 files changed, 163 insertions(+)
create mode 100644 drivers/tty/serial/8250/8250_dfl.c

diff --git a/drivers/tty/serial/8250/8250_dfl.c b/drivers/tty/serial/8250/8250_dfl.c
new file mode 100644
index 000000000000..0ee78c38a721
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_dfl.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for FPGA UART
+ *
+ * Copyright (C) 2022 Intel Corporation.
+ *
+ * Authors:
+ * Ananda Ravuri <ananda.ravuri@xxxxxxxxx>
+ * Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
+ */
+
+#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 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;
+ u64 *p;
+
+ p = dfh_get_u64_param_vals(dfl_dev, DFHv1_PARAM_ID_CLK_FRQ, &clk_freq, 1);
+ if (IS_ERR(p))
+ return dev_err_probe(dev, PTR_ERR(p), "missing CLK_FRQ param\n");
+
+ uart->port.uartclk = clk_freq;
+
+ p = dfh_get_u64_param_vals(dfl_dev, DFHv1_PARAM_ID_FIFO_LEN, &fifo_len, 1);
+ if (IS_ERR(p))
+ return dev_err_probe(dev, PTR_ERR(p), "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);
+ }
+
+ p = dfh_get_u64_param_vals(dfl_dev, DFHv1_PARAM_ID_REG_LAYOUT, &reg_layout, 1);
+ if (IS_ERR(p))
+ return dev_err_probe(dev, PTR_ERR(p), "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 b0f62345bc84..08af2acd4645 100644
--- 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 16650 UART. One or more Altera 16650 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 1615bfdde2a0..4e1a32812683 100644
--- 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
--
2.25.1