1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/mach-sa1100/ssp.c
4 *
5 * Copyright (C) 2003 Russell King.
6 *
7 * Generic SSP driver. This provides the generic core for simple
8 * IO-based SSP applications.
9 */
10#include <linux/module.h>
11#include <linux/kernel.h>
12#include <linux/sched.h>
13#include <linux/errno.h>
14#include <linux/interrupt.h>
15#include <linux/ioport.h>
16#include <linux/init.h>
17#include <linux/io.h>
18
19#include <mach/hardware.h>
20#include <mach/irqs.h>
21#include <asm/hardware/ssp.h>
22
23#define TIMEOUT 100000
24
25static irqreturn_t ssp_interrupt(int irq, void *dev_id)
26{
27 unsigned int status = Ser4SSSR;
28
29 if (status & SSSR_ROR)
30 printk(KERN_WARNING "SSP: receiver overrun\n");
31
32 Ser4SSSR = SSSR_ROR;
33
34 return status ? IRQ_HANDLED : IRQ_NONE;
35}
36
37/**
38 * ssp_write_word - write a word to the SSP port
39 * @data: 16-bit, MSB justified data to write.
40 *
41 * Wait for a free entry in the SSP transmit FIFO, and write a data
42 * word to the SSP port. Wait for the SSP port to start sending
43 * the data.
44 *
45 * The caller is expected to perform the necessary locking.
46 *
47 * Returns:
48 * %-ETIMEDOUT timeout occurred
49 * 0 success
50 */
51int ssp_write_word(u16 data)
52{
53 int timeout = TIMEOUT;
54
55 while (!(Ser4SSSR & SSSR_TNF)) {
56 if (!--timeout)
57 return -ETIMEDOUT;
58 cpu_relax();
59 }
60
61 Ser4SSDR = data;
62
63 timeout = TIMEOUT;
64 while (!(Ser4SSSR & SSSR_BSY)) {
65 if (!--timeout)
66 return -ETIMEDOUT;
67 cpu_relax();
68 }
69
70 return 0;
71}
72
73/**
74 * ssp_read_word - read a word from the SSP port
75 *
76 * Wait for a data word in the SSP receive FIFO, and return the
77 * received data. Data is LSB justified.
78 *
79 * Note: Currently, if data is not expected to be received, this
80 * function will wait for ever.
81 *
82 * The caller is expected to perform the necessary locking.
83 *
84 * Returns:
85 * %-ETIMEDOUT timeout occurred
86 * 16-bit data success
87 */
88int ssp_read_word(u16 *data)
89{
90 int timeout = TIMEOUT;
91
92 while (!(Ser4SSSR & SSSR_RNE)) {
93 if (!--timeout)
94 return -ETIMEDOUT;
95 cpu_relax();
96 }
97
98 *data = (u16)Ser4SSDR;
99
100 return 0;
101}
102
103/**
104 * ssp_flush - flush the transmit and receive FIFOs
105 *
106 * Wait for the SSP to idle, and ensure that the receive FIFO
107 * is empty.
108 *
109 * The caller is expected to perform the necessary locking.
110 *
111 * Returns:
112 * %-ETIMEDOUT timeout occurred
113 * 0 success
114 */
115int ssp_flush(void)
116{
117 int timeout = TIMEOUT * 2;
118
119 do {
120 while (Ser4SSSR & SSSR_RNE) {
121 if (!--timeout)
122 return -ETIMEDOUT;
123 (void) Ser4SSDR;
124 }
125 if (!--timeout)
126 return -ETIMEDOUT;
127 } while (Ser4SSSR & SSSR_BSY);
128
129 return 0;
130}
131
132/**
133 * ssp_enable - enable the SSP port
134 *
135 * Turn on the SSP port.
136 */
137void ssp_enable(void)
138{
139 Ser4SSCR0 |= SSCR0_SSE;
140}
141
142/**
143 * ssp_disable - shut down the SSP port
144 *
145 * Turn off the SSP port, optionally powering it down.
146 */
147void ssp_disable(void)
148{
149 Ser4SSCR0 &= ~SSCR0_SSE;
150}
151
152/**
153 * ssp_save_state - save the SSP configuration
154 * @ssp: pointer to structure to save SSP configuration
155 *
156 * Save the configured SSP state for suspend.
157 */
158void ssp_save_state(struct ssp_state *ssp)
159{
160 ssp->cr0 = Ser4SSCR0;
161 ssp->cr1 = Ser4SSCR1;
162
163 Ser4SSCR0 &= ~SSCR0_SSE;
164}
165
166/**
167 * ssp_restore_state - restore a previously saved SSP configuration
168 * @ssp: pointer to configuration saved by ssp_save_state
169 *
170 * Restore the SSP configuration saved previously by ssp_save_state.
171 */
172void ssp_restore_state(struct ssp_state *ssp)
173{
174 Ser4SSSR = SSSR_ROR;
175
176 Ser4SSCR0 = ssp->cr0 & ~SSCR0_SSE;
177 Ser4SSCR1 = ssp->cr1;
178 Ser4SSCR0 = ssp->cr0;
179}
180
181/**
182 * ssp_init - setup the SSP port
183 *
184 * initialise and claim resources for the SSP port.
185 *
186 * Returns:
187 * %-ENODEV if the SSP port is unavailable
188 * %-EBUSY if the resources are already in use
189 * %0 on success
190 */
191int ssp_init(void)
192{
193 int ret;
194
195 if (!(PPAR & PPAR_SPR) && (Ser4MCCR0 & MCCR0_MCE))
196 return -ENODEV;
197
198 if (!request_mem_region(__PREG(Ser4SSCR0), 0x18, "SSP")) {
199 return -EBUSY;
200 }
201
202 Ser4SSSR = SSSR_ROR;
203
204 ret = request_irq(IRQ_Ser4SSP, ssp_interrupt, 0, "SSP", NULL);
205 if (ret)
206 goto out_region;
207
208 return 0;
209
210 out_region:
211 release_mem_region(__PREG(Ser4SSCR0), 0x18);
212 return ret;
213}
214
215/**
216 * ssp_exit - undo the effects of ssp_init
217 *
218 * release and free resources for the SSP port.
219 */
220void ssp_exit(void)
221{
222 Ser4SSCR0 &= ~SSCR0_SSE;
223
224 free_irq(IRQ_Ser4SSP, NULL);
225 release_mem_region(__PREG(Ser4SSCR0), 0x18);
226}
227
228MODULE_AUTHOR("Russell King");
229MODULE_DESCRIPTION("SA11x0 SSP PIO driver");
230MODULE_LICENSE("GPL");
231
232EXPORT_SYMBOL(ssp_write_word);
233EXPORT_SYMBOL(ssp_read_word);
234EXPORT_SYMBOL(ssp_flush);
235EXPORT_SYMBOL(ssp_enable);
236EXPORT_SYMBOL(ssp_disable);
237EXPORT_SYMBOL(ssp_save_state);
238EXPORT_SYMBOL(ssp_restore_state);
239EXPORT_SYMBOL(ssp_init);
240EXPORT_SYMBOL(ssp_exit);
241

source code of linux/arch/arm/mach-sa1100/ssp.c