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