1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Xtensa xtfpga SPI controller driver
4 *
5 * Copyright (c) 2014 Cadence Design Systems Inc.
6 */
7
8 #include <linux/delay.h>
9 #include <linux/io.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/spi/spi.h>
14 #include <linux/spi/spi_bitbang.h>
15
16 #define XTFPGA_SPI_NAME "xtfpga_spi"
17
18 #define XTFPGA_SPI_START 0x0
19 #define XTFPGA_SPI_BUSY 0x4
20 #define XTFPGA_SPI_DATA 0x8
21
22 #define BUSY_WAIT_US 100
23
24 struct xtfpga_spi {
25 struct spi_bitbang bitbang;
26 void __iomem *regs;
27 u32 data;
28 unsigned data_sz;
29 };
30
xtfpga_spi_write32(const struct xtfpga_spi * spi,unsigned addr,u32 val)31 static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi,
32 unsigned addr, u32 val)
33 {
34 __raw_writel(val, spi->regs + addr);
35 }
36
xtfpga_spi_read32(const struct xtfpga_spi * spi,unsigned addr)37 static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi,
38 unsigned addr)
39 {
40 return __raw_readl(spi->regs + addr);
41 }
42
xtfpga_spi_wait_busy(struct xtfpga_spi * xspi)43 static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi)
44 {
45 unsigned i;
46
47 for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) &&
48 i < BUSY_WAIT_US; ++i)
49 udelay(1);
50 WARN_ON_ONCE(i == BUSY_WAIT_US);
51 }
52
xtfpga_spi_txrx_word(struct spi_device * spi,unsigned nsecs,u32 v,u8 bits,unsigned flags)53 static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
54 u32 v, u8 bits, unsigned flags)
55 {
56 struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
57
58 xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0));
59 xspi->data_sz += bits;
60 if (xspi->data_sz >= 16) {
61 xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA,
62 xspi->data >> (xspi->data_sz - 16));
63 xspi->data_sz -= 16;
64 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1);
65 xtfpga_spi_wait_busy(xspi);
66 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
67 }
68
69 return 0;
70 }
71
xtfpga_spi_chipselect(struct spi_device * spi,int is_on)72 static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on)
73 {
74 struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
75
76 WARN_ON(xspi->data_sz != 0);
77 xspi->data_sz = 0;
78 }
79
xtfpga_spi_probe(struct platform_device * pdev)80 static int xtfpga_spi_probe(struct platform_device *pdev)
81 {
82 struct xtfpga_spi *xspi;
83 int ret;
84 struct spi_master *master;
85
86 master = devm_spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi));
87 if (!master)
88 return -ENOMEM;
89
90 master->flags = SPI_CONTROLLER_NO_RX;
91 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
92 master->bus_num = pdev->dev.id;
93 master->dev.of_node = pdev->dev.of_node;
94
95 xspi = spi_master_get_devdata(master);
96 xspi->bitbang.master = master;
97 xspi->bitbang.chipselect = xtfpga_spi_chipselect;
98 xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
99 xspi->regs = devm_platform_ioremap_resource(pdev, 0);
100 if (IS_ERR(xspi->regs))
101 return PTR_ERR(xspi->regs);
102
103 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
104 usleep_range(1000, 2000);
105 if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
106 dev_err(&pdev->dev, "Device stuck in busy state\n");
107 return -EBUSY;
108 }
109
110 ret = spi_bitbang_start(&xspi->bitbang);
111 if (ret < 0) {
112 dev_err(&pdev->dev, "spi_bitbang_start failed\n");
113 return ret;
114 }
115
116 platform_set_drvdata(pdev, master);
117 return 0;
118 }
119
xtfpga_spi_remove(struct platform_device * pdev)120 static void xtfpga_spi_remove(struct platform_device *pdev)
121 {
122 struct spi_master *master = platform_get_drvdata(pdev);
123 struct xtfpga_spi *xspi = spi_master_get_devdata(master);
124
125 spi_bitbang_stop(&xspi->bitbang);
126 spi_master_put(master);
127 }
128
129 MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
130
131 #ifdef CONFIG_OF
132 static const struct of_device_id xtfpga_spi_of_match[] = {
133 { .compatible = "cdns,xtfpga-spi", },
134 {}
135 };
136 MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
137 #endif
138
139 static struct platform_driver xtfpga_spi_driver = {
140 .probe = xtfpga_spi_probe,
141 .remove_new = xtfpga_spi_remove,
142 .driver = {
143 .name = XTFPGA_SPI_NAME,
144 .of_match_table = of_match_ptr(xtfpga_spi_of_match),
145 },
146 };
147 module_platform_driver(xtfpga_spi_driver);
148
149 MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
150 MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
151 MODULE_LICENSE("GPL");
152
