2 * Copyright (C) 2014 Panasonic Corporation
3 * Copyright (C) 2015-2016 Socionext Inc.
4 * Author: Masahiro Yamada <yamada.masahiro@socionext.com>
6 * SPDX-License-Identifier: GPL-2.0+
9 #include <linux/delay.h>
10 #include <linux/errno.h>
12 #include <linux/sizes.h>
13 #include <linux/types.h>
18 struct uniphier_i2c_regs
{
19 u32 dtrm
; /* data transmission */
20 #define I2C_DTRM_STA (1 << 10)
21 #define I2C_DTRM_STO (1 << 9)
22 #define I2C_DTRM_NACK (1 << 8)
23 #define I2C_DTRM_RD (1 << 0)
24 u32 drec
; /* data reception */
25 #define I2C_DREC_STS (1 << 12)
26 #define I2C_DREC_LRB (1 << 11)
27 #define I2C_DREC_LAB (1 << 9)
28 u32 myad
; /* slave address */
29 u32 clk
; /* clock frequency control */
30 u32 brst
; /* bus reset */
31 #define I2C_BRST_FOEN (1 << 1)
32 #define I2C_BRST_BRST (1 << 0)
33 u32 hold
; /* hold time control */
34 u32 bsts
; /* bus status monitor */
35 u32 noise
; /* noise filter control */
36 u32 setup
; /* setup time control */
39 #define IOBUS_FREQ 100000000
41 struct uniphier_i2c_priv
{
43 struct uniphier_i2c_regs __iomem
*regs
; /* register base */
44 unsigned long input_clk
; /* master clock (Hz) */
45 unsigned long wait_us
; /* wait for every byte transfer (us) */
48 static int uniphier_i2c_probe(struct udevice
*dev
)
51 struct uniphier_i2c_priv
*priv
= dev_get_priv(dev
);
53 addr
= devfdt_get_addr(dev
);
54 if (addr
== FDT_ADDR_T_NONE
)
57 priv
->regs
= devm_ioremap(dev
, addr
, SZ_64
);
61 priv
->input_clk
= IOBUS_FREQ
;
66 writel(0x3, &priv
->regs
->brst
);
71 static int send_and_recv_byte(struct uniphier_i2c_priv
*priv
, u32 dtrm
)
73 writel(dtrm
, &priv
->regs
->dtrm
);
76 * This controller only provides interruption to inform the completion
77 * of each byte transfer. (No status register to poll it.)
78 * Unfortunately, U-Boot does not have a good support of interrupt.
81 udelay(priv
->wait_us
);
83 return readl(&priv
->regs
->drec
);
86 static int send_byte(struct uniphier_i2c_priv
*priv
, u32 dtrm
, bool *stop
)
91 drec
= send_and_recv_byte(priv
, dtrm
);
93 if (drec
& I2C_DREC_LAB
) {
94 dev_dbg(priv
->dev
, "uniphier_i2c: bus arbitration failed\n");
98 if (drec
& I2C_DREC_LRB
) {
99 dev_dbg(priv
->dev
, "uniphier_i2c: slave did not return ACK\n");
105 static int uniphier_i2c_transmit(struct uniphier_i2c_priv
*priv
, uint addr
,
106 uint len
, const u8
*buf
, bool *stop
)
110 dev_dbg(priv
->dev
, "%s: addr = %x, len = %d\n", __func__
, addr
, len
);
112 ret
= send_byte(priv
, I2C_DTRM_STA
| I2C_DTRM_NACK
| addr
<< 1, stop
);
117 ret
= send_byte(priv
, I2C_DTRM_NACK
| *buf
++, stop
);
124 writel(I2C_DTRM_STO
| I2C_DTRM_NACK
, &priv
->regs
->dtrm
);
129 static int uniphier_i2c_receive(struct uniphier_i2c_priv
*priv
, uint addr
,
130 uint len
, u8
*buf
, bool *stop
)
134 dev_dbg(priv
->dev
, "%s: addr = %x, len = %d\n", __func__
, addr
, len
);
136 ret
= send_byte(priv
, I2C_DTRM_STA
| I2C_DTRM_NACK
|
137 I2C_DTRM_RD
| addr
<< 1, stop
);
142 *buf
++ = send_and_recv_byte(priv
, len
? 0 : I2C_DTRM_NACK
);
146 writel(I2C_DTRM_STO
| I2C_DTRM_NACK
, &priv
->regs
->dtrm
);
151 static int uniphier_i2c_xfer(struct udevice
*bus
, struct i2c_msg
*msg
,
155 struct uniphier_i2c_priv
*priv
= dev_get_priv(bus
);
158 for (; nmsgs
> 0; nmsgs
--, msg
++) {
159 /* If next message is read, skip the stop condition */
160 stop
= nmsgs
> 1 && msg
[1].flags
& I2C_M_RD
? false : true;
162 if (msg
->flags
& I2C_M_RD
)
163 ret
= uniphier_i2c_receive(priv
, msg
->addr
, msg
->len
,
166 ret
= uniphier_i2c_transmit(priv
, msg
->addr
, msg
->len
,
176 static int uniphier_i2c_set_bus_speed(struct udevice
*bus
, unsigned int speed
)
178 struct uniphier_i2c_priv
*priv
= dev_get_priv(bus
);
180 /* max supported frequency is 400 kHz */
184 /* bus reset: make sure the bus is idle when change the frequency */
185 writel(0x1, &priv
->regs
->brst
);
187 writel((priv
->input_clk
/ speed
/ 2 << 16) | (priv
->input_clk
/ speed
),
190 writel(0x3, &priv
->regs
->brst
);
193 * Theoretically, each byte can be transferred in
194 * 1000000 * 9 / speed usec. For safety, wait more than double.
196 priv
->wait_us
= 20000000 / speed
;
202 static const struct dm_i2c_ops uniphier_i2c_ops
= {
203 .xfer
= uniphier_i2c_xfer
,
204 .set_bus_speed
= uniphier_i2c_set_bus_speed
,
207 static const struct udevice_id uniphier_i2c_of_match
[] = {
208 { .compatible
= "socionext,uniphier-i2c" },
212 U_BOOT_DRIVER(uniphier_i2c
) = {
213 .name
= "uniphier-i2c",
215 .of_match
= uniphier_i2c_of_match
,
216 .probe
= uniphier_i2c_probe
,
217 .priv_auto_alloc_size
= sizeof(struct uniphier_i2c_priv
),
218 .ops
= &uniphier_i2c_ops
,