1/*
2 * Altera SPI driver
3 *
4 * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
5 *
6 * Based on spi_s3c24xx.c, which is:
7 * Copyright (c) 2006 Ben Dooks
8 * Copyright (c) 2006 Simtec Electronics
9 *	Ben Dooks <ben@simtec.co.uk>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
15
16#include <linux/interrupt.h>
17#include <linux/errno.h>
18#include <linux/module.h>
19#include <linux/platform_device.h>
20#include <linux/spi/spi.h>
21#include <linux/spi/spi_bitbang.h>
22#include <linux/io.h>
23#include <linux/of.h>
24
25#define DRV_NAME "spi_altera"
26
27#define ALTERA_SPI_RXDATA	0
28#define ALTERA_SPI_TXDATA	4
29#define ALTERA_SPI_STATUS	8
30#define ALTERA_SPI_CONTROL	12
31#define ALTERA_SPI_SLAVE_SEL	20
32
33#define ALTERA_SPI_STATUS_ROE_MSK	0x8
34#define ALTERA_SPI_STATUS_TOE_MSK	0x10
35#define ALTERA_SPI_STATUS_TMT_MSK	0x20
36#define ALTERA_SPI_STATUS_TRDY_MSK	0x40
37#define ALTERA_SPI_STATUS_RRDY_MSK	0x80
38#define ALTERA_SPI_STATUS_E_MSK		0x100
39
40#define ALTERA_SPI_CONTROL_IROE_MSK	0x8
41#define ALTERA_SPI_CONTROL_ITOE_MSK	0x10
42#define ALTERA_SPI_CONTROL_ITRDY_MSK	0x40
43#define ALTERA_SPI_CONTROL_IRRDY_MSK	0x80
44#define ALTERA_SPI_CONTROL_IE_MSK	0x100
45#define ALTERA_SPI_CONTROL_SSO_MSK	0x400
46
47struct altera_spi {
48	/* bitbang has to be first */
49	struct spi_bitbang bitbang;
50	struct completion done;
51
52	void __iomem *base;
53	int irq;
54	int len;
55	int count;
56	int bytes_per_word;
57	unsigned long imr;
58
59	/* data buffers */
60	const unsigned char *tx;
61	unsigned char *rx;
62};
63
64static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
65{
66	return spi_master_get_devdata(sdev->master);
67}
68
69static void altera_spi_chipsel(struct spi_device *spi, int value)
70{
71	struct altera_spi *hw = altera_spi_to_hw(spi);
72
73	if (spi->mode & SPI_CS_HIGH) {
74		switch (value) {
75		case BITBANG_CS_INACTIVE:
76			writel(1 << spi->chip_select,
77			       hw->base + ALTERA_SPI_SLAVE_SEL);
78			hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
79			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
80			break;
81
82		case BITBANG_CS_ACTIVE:
83			hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
84			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
85			writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
86			break;
87		}
88	} else {
89		switch (value) {
90		case BITBANG_CS_INACTIVE:
91			hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
92			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
93			break;
94
95		case BITBANG_CS_ACTIVE:
96			writel(1 << spi->chip_select,
97			       hw->base + ALTERA_SPI_SLAVE_SEL);
98			hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
99			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
100			break;
101		}
102	}
103}
104
105static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
106{
107	if (hw->tx) {
108		switch (hw->bytes_per_word) {
109		case 1:
110			return hw->tx[count];
111		case 2:
112			return (hw->tx[count * 2]
113				| (hw->tx[count * 2 + 1] << 8));
114		}
115	}
116	return 0;
117}
118
119static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
120{
121	struct altera_spi *hw = altera_spi_to_hw(spi);
122
123	hw->tx = t->tx_buf;
124	hw->rx = t->rx_buf;
125	hw->count = 0;
126	hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
127	hw->len = t->len / hw->bytes_per_word;
128
129	if (hw->irq >= 0) {
130		/* enable receive interrupt */
131		hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
132		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
133
134		/* send the first byte */
135		writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
136
137		wait_for_completion(&hw->done);
138		/* disable receive interrupt */
139		hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
140		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
141	} else {
142		while (hw->count < hw->len) {
143			unsigned int rxd;
144
145			writel(hw_txbyte(hw, hw->count),
146			       hw->base + ALTERA_SPI_TXDATA);
147
148			while (!(readl(hw->base + ALTERA_SPI_STATUS) &
149				 ALTERA_SPI_STATUS_RRDY_MSK))
150				cpu_relax();
151
152			rxd = readl(hw->base + ALTERA_SPI_RXDATA);
153			if (hw->rx) {
154				switch (hw->bytes_per_word) {
155				case 1:
156					hw->rx[hw->count] = rxd;
157					break;
158				case 2:
159					hw->rx[hw->count * 2] = rxd;
160					hw->rx[hw->count * 2 + 1] = rxd >> 8;
161					break;
162				}
163			}
164
165			hw->count++;
166		}
167	}
168
169	return hw->count * hw->bytes_per_word;
170}
171
172static irqreturn_t altera_spi_irq(int irq, void *dev)
173{
174	struct altera_spi *hw = dev;
175	unsigned int rxd;
176
177	rxd = readl(hw->base + ALTERA_SPI_RXDATA);
178	if (hw->rx) {
179		switch (hw->bytes_per_word) {
180		case 1:
181			hw->rx[hw->count] = rxd;
182			break;
183		case 2:
184			hw->rx[hw->count * 2] = rxd;
185			hw->rx[hw->count * 2 + 1] = rxd >> 8;
186			break;
187		}
188	}
189
190	hw->count++;
191
192	if (hw->count < hw->len)
193		writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
194	else
195		complete(&hw->done);
196
197	return IRQ_HANDLED;
198}
199
200static int altera_spi_probe(struct platform_device *pdev)
201{
202	struct altera_spi *hw;
203	struct spi_master *master;
204	struct resource *res;
205	int err = -ENODEV;
206
207	master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
208	if (!master)
209		return err;
210
211	/* setup the master state. */
212	master->bus_num = pdev->id;
213	master->num_chipselect = 16;
214	master->mode_bits = SPI_CS_HIGH;
215	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
216	master->dev.of_node = pdev->dev.of_node;
217
218	hw = spi_master_get_devdata(master);
219	platform_set_drvdata(pdev, hw);
220
221	/* setup the state for the bitbang driver */
222	hw->bitbang.master = master;
223	hw->bitbang.chipselect = altera_spi_chipsel;
224	hw->bitbang.txrx_bufs = altera_spi_txrx;
225
226	/* find and map our resources */
227	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
228	hw->base = devm_ioremap_resource(&pdev->dev, res);
229	if (IS_ERR(hw->base)) {
230		err = PTR_ERR(hw->base);
231		goto exit;
232	}
233	/* program defaults into the registers */
234	hw->imr = 0;		/* disable spi interrupts */
235	writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
236	writel(0, hw->base + ALTERA_SPI_STATUS);	/* clear status reg */
237	if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
238		readl(hw->base + ALTERA_SPI_RXDATA);	/* flush rxdata */
239	/* irq is optional */
240	hw->irq = platform_get_irq(pdev, 0);
241	if (hw->irq >= 0) {
242		init_completion(&hw->done);
243		err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
244				       pdev->name, hw);
245		if (err)
246			goto exit;
247	}
248
249	/* register our spi controller */
250	err = spi_bitbang_start(&hw->bitbang);
251	if (err)
252		goto exit;
253	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
254
255	return 0;
256exit:
257	spi_master_put(master);
258	return err;
259}
260
261static int altera_spi_remove(struct platform_device *dev)
262{
263	struct altera_spi *hw = platform_get_drvdata(dev);
264	struct spi_master *master = hw->bitbang.master;
265
266	spi_bitbang_stop(&hw->bitbang);
267	spi_master_put(master);
268	return 0;
269}
270
271#ifdef CONFIG_OF
272static const struct of_device_id altera_spi_match[] = {
273	{ .compatible = "ALTR,spi-1.0", },
274	{ .compatible = "altr,spi-1.0", },
275	{},
276};
277MODULE_DEVICE_TABLE(of, altera_spi_match);
278#endif /* CONFIG_OF */
279
280static struct platform_driver altera_spi_driver = {
281	.probe = altera_spi_probe,
282	.remove = altera_spi_remove,
283	.driver = {
284		.name = DRV_NAME,
285		.pm = NULL,
286		.of_match_table = of_match_ptr(altera_spi_match),
287	},
288};
289module_platform_driver(altera_spi_driver);
290
291MODULE_DESCRIPTION("Altera SPI driver");
292MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
293MODULE_LICENSE("GPL");
294MODULE_ALIAS("platform:" DRV_NAME);
295