1/*
2 * SH SCI SPI interface
3 *
4 * Copyright (c) 2008 Magnus Damm
5 *
6 * Based on S3C24XX GPIO based SPI driver, which is:
7 *   Copyright (c) 2006 Ben Dooks
8 *   Copyright (c) 2006 Simtec Electronics
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 *
14 */
15
16#include <linux/kernel.h>
17#include <linux/delay.h>
18#include <linux/spinlock.h>
19#include <linux/platform_device.h>
20
21#include <linux/spi/spi.h>
22#include <linux/spi/spi_bitbang.h>
23#include <linux/module.h>
24
25#include <asm/spi.h>
26#include <asm/io.h>
27
28struct sh_sci_spi {
29	struct spi_bitbang bitbang;
30
31	void __iomem *membase;
32	unsigned char val;
33	struct sh_spi_info *info;
34	struct platform_device *dev;
35};
36
37#define SCSPTR(sp)	(sp->membase + 0x1c)
38#define PIN_SCK		(1 << 2)
39#define PIN_TXD		(1 << 0)
40#define PIN_RXD		PIN_TXD
41#define PIN_INIT	((1 << 1) | (1 << 3) | PIN_SCK | PIN_TXD)
42
43static inline void setbits(struct sh_sci_spi *sp, int bits, int on)
44{
45	/*
46	 * We are the only user of SCSPTR so no locking is required.
47	 * Reading bit 2 and 0 in SCSPTR gives pin state as input.
48	 * Writing the same bits sets the output value.
49	 * This makes regular read-modify-write difficult so we
50	 * use sp->val to keep track of the latest register value.
51	 */
52
53	if (on)
54		sp->val |= bits;
55	else
56		sp->val &= ~bits;
57
58	iowrite8(sp->val, SCSPTR(sp));
59}
60
61static inline void setsck(struct spi_device *dev, int on)
62{
63	setbits(spi_master_get_devdata(dev->master), PIN_SCK, on);
64}
65
66static inline void setmosi(struct spi_device *dev, int on)
67{
68	setbits(spi_master_get_devdata(dev->master), PIN_TXD, on);
69}
70
71static inline u32 getmiso(struct spi_device *dev)
72{
73	struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
74
75	return (ioread8(SCSPTR(sp)) & PIN_RXD) ? 1 : 0;
76}
77
78#define spidelay(x) ndelay(x)
79
80#include "spi-bitbang-txrx.h"
81
82static u32 sh_sci_spi_txrx_mode0(struct spi_device *spi,
83				      unsigned nsecs, u32 word, u8 bits)
84{
85	return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
86}
87
88static u32 sh_sci_spi_txrx_mode1(struct spi_device *spi,
89				      unsigned nsecs, u32 word, u8 bits)
90{
91	return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits);
92}
93
94static u32 sh_sci_spi_txrx_mode2(struct spi_device *spi,
95				      unsigned nsecs, u32 word, u8 bits)
96{
97	return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits);
98}
99
100static u32 sh_sci_spi_txrx_mode3(struct spi_device *spi,
101				      unsigned nsecs, u32 word, u8 bits)
102{
103	return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
104}
105
106static void sh_sci_spi_chipselect(struct spi_device *dev, int value)
107{
108	struct sh_sci_spi *sp = spi_master_get_devdata(dev->master);
109
110	if (sp->info->chip_select)
111		(sp->info->chip_select)(sp->info, dev->chip_select, value);
112}
113
114static int sh_sci_spi_probe(struct platform_device *dev)
115{
116	struct resource	*r;
117	struct spi_master *master;
118	struct sh_sci_spi *sp;
119	int ret;
120
121	master = spi_alloc_master(&dev->dev, sizeof(struct sh_sci_spi));
122	if (master == NULL) {
123		dev_err(&dev->dev, "failed to allocate spi master\n");
124		ret = -ENOMEM;
125		goto err0;
126	}
127
128	sp = spi_master_get_devdata(master);
129
130	platform_set_drvdata(dev, sp);
131	sp->info = dev_get_platdata(&dev->dev);
132	if (!sp->info) {
133		dev_err(&dev->dev, "platform data is missing\n");
134		ret = -ENOENT;
135		goto err1;
136	}
137
138	/* setup spi bitbang adaptor */
139	sp->bitbang.master = master;
140	sp->bitbang.master->bus_num = sp->info->bus_num;
141	sp->bitbang.master->num_chipselect = sp->info->num_chipselect;
142	sp->bitbang.chipselect = sh_sci_spi_chipselect;
143
144	sp->bitbang.txrx_word[SPI_MODE_0] = sh_sci_spi_txrx_mode0;
145	sp->bitbang.txrx_word[SPI_MODE_1] = sh_sci_spi_txrx_mode1;
146	sp->bitbang.txrx_word[SPI_MODE_2] = sh_sci_spi_txrx_mode2;
147	sp->bitbang.txrx_word[SPI_MODE_3] = sh_sci_spi_txrx_mode3;
148
149	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
150	if (r == NULL) {
151		ret = -ENOENT;
152		goto err1;
153	}
154	sp->membase = ioremap(r->start, resource_size(r));
155	if (!sp->membase) {
156		ret = -ENXIO;
157		goto err1;
158	}
159	sp->val = ioread8(SCSPTR(sp));
160	setbits(sp, PIN_INIT, 1);
161
162	ret = spi_bitbang_start(&sp->bitbang);
163	if (!ret)
164		return 0;
165
166	setbits(sp, PIN_INIT, 0);
167	iounmap(sp->membase);
168 err1:
169	spi_master_put(sp->bitbang.master);
170 err0:
171	return ret;
172}
173
174static int sh_sci_spi_remove(struct platform_device *dev)
175{
176	struct sh_sci_spi *sp = platform_get_drvdata(dev);
177
178	spi_bitbang_stop(&sp->bitbang);
179	setbits(sp, PIN_INIT, 0);
180	iounmap(sp->membase);
181	spi_master_put(sp->bitbang.master);
182	return 0;
183}
184
185static struct platform_driver sh_sci_spi_drv = {
186	.probe		= sh_sci_spi_probe,
187	.remove		= sh_sci_spi_remove,
188	.driver		= {
189		.name	= "spi_sh_sci",
190	},
191};
192module_platform_driver(sh_sci_spi_drv);
193
194MODULE_DESCRIPTION("SH SCI SPI Driver");
195MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
196MODULE_LICENSE("GPL");
197MODULE_ALIAS("platform:spi_sh_sci");
198