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 | |
31 | static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi, |
32 | unsigned addr, u32 val) |
33 | { |
34 | __raw_writel(val, addr: spi->regs + addr); |
35 | } |
36 | |
37 | static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi, |
38 | unsigned addr) |
39 | { |
40 | return __raw_readl(addr: spi->regs + addr); |
41 | } |
42 | |
43 | static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi) |
44 | { |
45 | unsigned i; |
46 | |
47 | for (i = 0; xtfpga_spi_read32(spi: xspi, XTFPGA_SPI_BUSY) && |
48 | i < BUSY_WAIT_US; ++i) |
49 | udelay(1); |
50 | WARN_ON_ONCE(i == BUSY_WAIT_US); |
51 | } |
52 | |
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_controller_get_devdata(ctlr: spi->controller); |
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(spi: xspi, XTFPGA_SPI_DATA, |
62 | val: xspi->data >> (xspi->data_sz - 16)); |
63 | xspi->data_sz -= 16; |
64 | xtfpga_spi_write32(spi: xspi, XTFPGA_SPI_START, val: 1); |
65 | xtfpga_spi_wait_busy(xspi); |
66 | xtfpga_spi_write32(spi: xspi, XTFPGA_SPI_START, val: 0); |
67 | } |
68 | |
69 | return 0; |
70 | } |
71 | |
72 | static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on) |
73 | { |
74 | struct xtfpga_spi *xspi = spi_controller_get_devdata(ctlr: spi->controller); |
75 | |
76 | WARN_ON(xspi->data_sz != 0); |
77 | xspi->data_sz = 0; |
78 | } |
79 | |
80 | static int xtfpga_spi_probe(struct platform_device *pdev) |
81 | { |
82 | struct xtfpga_spi *xspi; |
83 | int ret; |
84 | struct spi_controller *host; |
85 | |
86 | host = devm_spi_alloc_host(dev: &pdev->dev, size: sizeof(struct xtfpga_spi)); |
87 | if (!host) |
88 | return -ENOMEM; |
89 | |
90 | host->flags = SPI_CONTROLLER_NO_RX; |
91 | host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16); |
92 | host->bus_num = pdev->dev.id; |
93 | host->dev.of_node = pdev->dev.of_node; |
94 | |
95 | xspi = spi_controller_get_devdata(ctlr: host); |
96 | xspi->bitbang.ctlr = host; |
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, index: 0); |
100 | if (IS_ERR(ptr: xspi->regs)) |
101 | return PTR_ERR(ptr: xspi->regs); |
102 | |
103 | xtfpga_spi_write32(spi: xspi, XTFPGA_SPI_START, val: 0); |
104 | usleep_range(min: 1000, max: 2000); |
105 | if (xtfpga_spi_read32(spi: 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(spi: &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, data: host); |
117 | return 0; |
118 | } |
119 | |
120 | static void xtfpga_spi_remove(struct platform_device *pdev) |
121 | { |
122 | struct spi_controller *host = platform_get_drvdata(pdev); |
123 | struct xtfpga_spi *xspi = spi_controller_get_devdata(ctlr: host); |
124 | |
125 | spi_bitbang_stop(spi: &xspi->bitbang); |
126 | spi_controller_put(ctlr: host); |
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 | |