1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Driver for FPGA UART
4 *
5 * Copyright (C) 2022 Intel Corporation.
6 *
7 * Authors:
8 * Ananda Ravuri <ananda.ravuri@intel.com>
9 * Matthew Gerlach <matthew.gerlach@linux.intel.com>
10 */
11
12#include <linux/bitfield.h>
13#include <linux/device.h>
14#include <linux/dfl.h>
15#include <linux/errno.h>
16#include <linux/ioport.h>
17#include <linux/module.h>
18#include <linux/mod_devicetable.h>
19#include <linux/types.h>
20
21#include <linux/serial.h>
22#include <linux/serial_8250.h>
23
24#define DFHv1_PARAM_ID_CLK_FRQ 0x2
25#define DFHv1_PARAM_ID_FIFO_LEN 0x3
26
27#define DFHv1_PARAM_ID_REG_LAYOUT 0x4
28#define DFHv1_PARAM_REG_LAYOUT_WIDTH GENMASK_ULL(63, 32)
29#define DFHv1_PARAM_REG_LAYOUT_SHIFT GENMASK_ULL(31, 0)
30
31struct dfl_uart {
32 int line;
33};
34
35static int dfh_get_u64_param_val(struct dfl_device *dfl_dev, int param_id, u64 *pval)
36{
37 size_t psize;
38 u64 *p;
39
40 p = dfh_find_param(dfl_dev, param_id, pcount: &psize);
41 if (IS_ERR(ptr: p))
42 return PTR_ERR(ptr: p);
43
44 if (psize != sizeof(*pval))
45 return -EINVAL;
46
47 *pval = *p;
48
49 return 0;
50}
51
52static int dfl_uart_get_params(struct dfl_device *dfl_dev, struct uart_8250_port *uart)
53{
54 struct device *dev = &dfl_dev->dev;
55 u64 fifo_len, clk_freq, reg_layout;
56 u32 reg_width;
57 int ret;
58
59 ret = dfh_get_u64_param_val(dfl_dev, DFHv1_PARAM_ID_CLK_FRQ, pval: &clk_freq);
60 if (ret)
61 return dev_err_probe(dev, err: ret, fmt: "missing CLK_FRQ param\n");
62
63 uart->port.uartclk = clk_freq;
64
65 ret = dfh_get_u64_param_val(dfl_dev, DFHv1_PARAM_ID_FIFO_LEN, pval: &fifo_len);
66 if (ret)
67 return dev_err_probe(dev, err: ret, fmt: "missing FIFO_LEN param\n");
68
69 switch (fifo_len) {
70 case 32:
71 uart->port.type = PORT_ALTR_16550_F32;
72 break;
73
74 case 64:
75 uart->port.type = PORT_ALTR_16550_F64;
76 break;
77
78 case 128:
79 uart->port.type = PORT_ALTR_16550_F128;
80 break;
81
82 default:
83 return dev_err_probe(dev, err: -EINVAL, fmt: "unsupported FIFO_LEN %llu\n", fifo_len);
84 }
85
86 ret = dfh_get_u64_param_val(dfl_dev, DFHv1_PARAM_ID_REG_LAYOUT, pval: &reg_layout);
87 if (ret)
88 return dev_err_probe(dev, err: ret, fmt: "missing REG_LAYOUT param\n");
89
90 uart->port.regshift = FIELD_GET(DFHv1_PARAM_REG_LAYOUT_SHIFT, reg_layout);
91 reg_width = FIELD_GET(DFHv1_PARAM_REG_LAYOUT_WIDTH, reg_layout);
92 switch (reg_width) {
93 case 4:
94 uart->port.iotype = UPIO_MEM32;
95 break;
96
97 case 2:
98 uart->port.iotype = UPIO_MEM16;
99 break;
100
101 default:
102 return dev_err_probe(dev, err: -EINVAL, fmt: "unsupported reg-width %u\n", reg_width);
103
104 }
105
106 return 0;
107}
108
109static int dfl_uart_probe(struct dfl_device *dfl_dev)
110{
111 struct device *dev = &dfl_dev->dev;
112 struct uart_8250_port uart = { };
113 struct dfl_uart *dfluart;
114 int ret;
115
116 uart.port.flags = UPF_IOREMAP;
117 uart.port.mapbase = dfl_dev->mmio_res.start;
118 uart.port.mapsize = resource_size(res: &dfl_dev->mmio_res);
119
120 ret = dfl_uart_get_params(dfl_dev, uart: &uart);
121 if (ret < 0)
122 return dev_err_probe(dev, err: ret, fmt: "failed uart feature walk\n");
123
124 if (dfl_dev->num_irqs == 1)
125 uart.port.irq = dfl_dev->irqs[0];
126
127 dfluart = devm_kzalloc(dev, size: sizeof(*dfluart), GFP_KERNEL);
128 if (!dfluart)
129 return -ENOMEM;
130
131 dfluart->line = serial8250_register_8250_port(&uart);
132 if (dfluart->line < 0)
133 return dev_err_probe(dev, err: dfluart->line, fmt: "unable to register 8250 port.\n");
134
135 dev_set_drvdata(dev, data: dfluart);
136
137 return 0;
138}
139
140static void dfl_uart_remove(struct dfl_device *dfl_dev)
141{
142 struct dfl_uart *dfluart = dev_get_drvdata(dev: &dfl_dev->dev);
143
144 serial8250_unregister_port(line: dfluart->line);
145}
146
147#define FME_FEATURE_ID_UART 0x24
148
149static const struct dfl_device_id dfl_uart_ids[] = {
150 { FME_ID, FME_FEATURE_ID_UART },
151 { }
152};
153MODULE_DEVICE_TABLE(dfl, dfl_uart_ids);
154
155static struct dfl_driver dfl_uart_driver = {
156 .drv = {
157 .name = "dfl-uart",
158 },
159 .id_table = dfl_uart_ids,
160 .probe = dfl_uart_probe,
161 .remove = dfl_uart_remove,
162};
163module_dfl_driver(dfl_uart_driver);
164
165MODULE_DESCRIPTION("DFL Intel UART driver");
166MODULE_AUTHOR("Intel Corporation");
167MODULE_LICENSE("GPL");
168

source code of linux/drivers/tty/serial/8250/8250_dfl.c