2 * Xtensa xtfpga SPI controller driver
4 * Copyright (c) 2014 Cadence Design Systems Inc.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/delay.h>
13 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/spi/spi.h>
17 #include <linux/spi/spi_bitbang.h>
19 #define XTFPGA_SPI_NAME "xtfpga_spi"
21 #define XTFPGA_SPI_START 0x0
22 #define XTFPGA_SPI_BUSY 0x4
23 #define XTFPGA_SPI_DATA 0x8
25 #define BUSY_WAIT_US 100
28 struct spi_bitbang bitbang;
34 static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi,
35 unsigned addr, u32 val)
37 iowrite32(val, spi->regs + addr);
40 static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi,
43 return ioread32(spi->regs + addr);
46 static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi)
49 for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) &&
50 i < BUSY_WAIT_US; ++i)
52 WARN_ON_ONCE(i == BUSY_WAIT_US);
55 static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
58 struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
60 xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0));
61 xspi->data_sz += bits;
62 if (xspi->data_sz >= 16) {
63 xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA,
64 xspi->data >> (xspi->data_sz - 16));
66 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1);
67 xtfpga_spi_wait_busy(xspi);
68 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
74 static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on)
76 struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
78 WARN_ON(xspi->data_sz != 0);
82 static int xtfpga_spi_probe(struct platform_device *pdev)
84 struct xtfpga_spi *xspi;
87 struct spi_master *master;
89 master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi));
93 master->flags = SPI_MASTER_NO_RX;
94 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
95 master->bus_num = pdev->dev.id;
96 master->dev.of_node = pdev->dev.of_node;
98 xspi = spi_master_get_devdata(master);
99 xspi->bitbang.master = master;
100 xspi->bitbang.chipselect = xtfpga_spi_chipselect;
101 xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
103 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
105 dev_err(&pdev->dev, "No memory resource\n");
109 xspi->regs = devm_ioremap_resource(&pdev->dev, mem);
110 if (IS_ERR(xspi->regs)) {
111 ret = PTR_ERR(xspi->regs);
115 xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
116 usleep_range(1000, 2000);
117 if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
118 dev_err(&pdev->dev, "Device stuck in busy state\n");
123 ret = spi_bitbang_start(&xspi->bitbang);
125 dev_err(&pdev->dev, "spi_bitbang_start failed\n");
129 platform_set_drvdata(pdev, master);
132 spi_master_put(master);
136 static int xtfpga_spi_remove(struct platform_device *pdev)
138 struct spi_master *master = platform_get_drvdata(pdev);
139 struct xtfpga_spi *xspi = spi_master_get_devdata(master);
141 spi_bitbang_stop(&xspi->bitbang);
142 spi_master_put(master);
147 MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
150 static const struct of_device_id xtfpga_spi_of_match[] = {
151 { .compatible = "cdns,xtfpga-spi", },
154 MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
157 static struct platform_driver xtfpga_spi_driver = {
158 .probe = xtfpga_spi_probe,
159 .remove = xtfpga_spi_remove,
161 .name = XTFPGA_SPI_NAME,
162 .owner = THIS_MODULE,
163 .of_match_table = of_match_ptr(xtfpga_spi_of_match),
166 module_platform_driver(xtfpga_spi_driver);
168 MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
169 MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
170 MODULE_LICENSE("GPL");