1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Xilinx AXI I2C driver
4 *
5 * Copyright (C) 2018 Marek Vasut <marex@denx.de>
6 *
7 * Based on Linux 4.14.y i2c-xiic.c
8 * Copyright (c) 2002-2007 Xilinx Inc.
9 * Copyright (c) 2009-2010 Intel Corporation
10 */
11
12 #include <common.h>
13 #include <clk.h>
14 #include <dm.h>
15 #include <i2c.h>
16 #include <wait_bit.h>
17 #include <asm/io.h>
18
19 struct xilinx_xiic_priv {
20 void __iomem *base;
21 struct clk clk;
22 };
23
24 #define XIIC_MSB_OFFSET 0
25 #define XIIC_REG_OFFSET (0x100+XIIC_MSB_OFFSET)
26
27 /*
28 * Register offsets in bytes from RegisterBase. Three is added to the
29 * base offset to access LSB (IBM style) of the word
30 */
31 #define XIIC_CR_REG_OFFSET (0x00+XIIC_REG_OFFSET) /* Control Register */
32 #define XIIC_SR_REG_OFFSET (0x04+XIIC_REG_OFFSET) /* Status Register */
33 #define XIIC_DTR_REG_OFFSET (0x08+XIIC_REG_OFFSET) /* Data Tx Register */
34 #define XIIC_DRR_REG_OFFSET (0x0C+XIIC_REG_OFFSET) /* Data Rx Register */
35 #define XIIC_ADR_REG_OFFSET (0x10+XIIC_REG_OFFSET) /* Address Register */
36 #define XIIC_TFO_REG_OFFSET (0x14+XIIC_REG_OFFSET) /* Tx FIFO Occupancy */
37 #define XIIC_RFO_REG_OFFSET (0x18+XIIC_REG_OFFSET) /* Rx FIFO Occupancy */
38 #define XIIC_TBA_REG_OFFSET (0x1C+XIIC_REG_OFFSET) /* 10 Bit Address reg */
39 #define XIIC_RFD_REG_OFFSET (0x20+XIIC_REG_OFFSET) /* Rx FIFO Depth reg */
40 #define XIIC_GPO_REG_OFFSET (0x24+XIIC_REG_OFFSET) /* Output Register */
41
42 /* Control Register masks */
43 #define XIIC_CR_ENABLE_DEVICE_MASK 0x01 /* Device enable = 1 */
44 #define XIIC_CR_TX_FIFO_RESET_MASK 0x02 /* Transmit FIFO reset=1 */
45 #define XIIC_CR_MSMS_MASK 0x04 /* Master starts Txing=1 */
46 #define XIIC_CR_DIR_IS_TX_MASK 0x08 /* Dir of tx. Txing=1 */
47 #define XIIC_CR_NO_ACK_MASK 0x10 /* Tx Ack. NO ack = 1 */
48 #define XIIC_CR_REPEATED_START_MASK 0x20 /* Repeated start = 1 */
49 #define XIIC_CR_GENERAL_CALL_MASK 0x40 /* Gen Call enabled = 1 */
50
51 /* Status Register masks */
52 #define XIIC_SR_GEN_CALL_MASK 0x01 /* 1=a mstr issued a GC */
53 #define XIIC_SR_ADDR_AS_SLAVE_MASK 0x02 /* 1=when addr as slave */
54 #define XIIC_SR_BUS_BUSY_MASK 0x04 /* 1 = bus is busy */
55 #define XIIC_SR_MSTR_RDING_SLAVE_MASK 0x08 /* 1=Dir: mstr <-- slave */
56 #define XIIC_SR_TX_FIFO_FULL_MASK 0x10 /* 1 = Tx FIFO full */
57 #define XIIC_SR_RX_FIFO_FULL_MASK 0x20 /* 1 = Rx FIFO full */
58 #define XIIC_SR_RX_FIFO_EMPTY_MASK 0x40 /* 1 = Rx FIFO empty */
59 #define XIIC_SR_TX_FIFO_EMPTY_MASK 0x80 /* 1 = Tx FIFO empty */
60
61 /* Interrupt Status Register masks Interrupt occurs when... */
62 #define XIIC_INTR_ARB_LOST_MASK 0x01 /* 1 = arbitration lost */
63 #define XIIC_INTR_TX_ERROR_MASK 0x02 /* 1=Tx error/msg complete */
64 #define XIIC_INTR_TX_EMPTY_MASK 0x04 /* 1 = Tx FIFO/reg empty */
65 #define XIIC_INTR_RX_FULL_MASK 0x08 /* 1=Rx FIFO/reg=OCY level */
66 #define XIIC_INTR_BNB_MASK 0x10 /* 1 = Bus not busy */
67 #define XIIC_INTR_AAS_MASK 0x20 /* 1 = when addr as slave */
68 #define XIIC_INTR_NAAS_MASK 0x40 /* 1 = not addr as slave */
69 #define XIIC_INTR_TX_HALF_MASK 0x80 /* 1 = TX FIFO half empty */
70
71 /* The following constants specify the depth of the FIFOs */
72 #define IIC_RX_FIFO_DEPTH 16 /* Rx fifo capacity */
73 #define IIC_TX_FIFO_DEPTH 16 /* Tx fifo capacity */
74
75 /*
76 * Tx Fifo upper bit masks.
77 */
78 #define XIIC_TX_DYN_START_MASK 0x0100 /* 1 = Set dynamic start */
79 #define XIIC_TX_DYN_STOP_MASK 0x0200 /* 1 = Set dynamic stop */
80
81 /*
82 * The following constants define the register offsets for the Interrupt
83 * registers. There are some holes in the memory map for reserved addresses
84 * to allow other registers to be added and still match the memory map of the
85 * interrupt controller registers
86 */
87 #define XIIC_DGIER_OFFSET 0x1C /* Device Global Interrupt Enable Register */
88 #define XIIC_IISR_OFFSET 0x20 /* Interrupt Status Register */
89 #define XIIC_IIER_OFFSET 0x28 /* Interrupt Enable Register */
90 #define XIIC_RESETR_OFFSET 0x40 /* Reset Register */
91
92 #define XIIC_RESET_MASK 0xAUL
93
i2c_8bit_addr_from_flags(uint addr,u16 flags)94 static u8 i2c_8bit_addr_from_flags(uint addr, u16 flags)
95 {
96 return (addr << 1) | (flags & I2C_M_RD ? 1 : 0);
97 }
98
xiic_irq_clr(struct xilinx_xiic_priv * priv,u32 mask)99 static void xiic_irq_clr(struct xilinx_xiic_priv *priv, u32 mask)
100 {
101 u32 isr = readl(priv->base + XIIC_IISR_OFFSET);
102
103 writel(isr & mask, priv->base + XIIC_IISR_OFFSET);
104 }
105
xiic_read_rx(struct xilinx_xiic_priv * priv,struct i2c_msg * msg,int nmsgs)106 static int xiic_read_rx(struct xilinx_xiic_priv *priv,
107 struct i2c_msg *msg, int nmsgs)
108 {
109 u8 bytes_in_fifo;
110 u32 pos = 0;
111 int i, ret;
112
113 while (pos < msg->len) {
114 ret = wait_for_bit_8(priv->base + XIIC_SR_REG_OFFSET,
115 XIIC_SR_RX_FIFO_EMPTY_MASK, false,
116 1000, true);
117 if (ret)
118 return ret;
119
120 bytes_in_fifo = readb(priv->base + XIIC_RFO_REG_OFFSET) + 1;
121
122 if (bytes_in_fifo > msg->len)
123 bytes_in_fifo = msg->len;
124
125 for (i = 0; i < bytes_in_fifo; i++) {
126 msg->buf[pos++] = readb(priv->base +
127 XIIC_DRR_REG_OFFSET);
128 }
129 }
130
131 return 0;
132 }
133
xiic_tx_fifo_space(struct xilinx_xiic_priv * priv)134 static int xiic_tx_fifo_space(struct xilinx_xiic_priv *priv)
135 {
136 /* return the actual space left in the FIFO */
137 return IIC_TX_FIFO_DEPTH - readb(priv->base + XIIC_TFO_REG_OFFSET) - 1;
138 }
139
xiic_fill_tx_fifo(struct xilinx_xiic_priv * priv,struct i2c_msg * msg,int nmsgs)140 static void xiic_fill_tx_fifo(struct xilinx_xiic_priv *priv,
141 struct i2c_msg *msg, int nmsgs)
142 {
143 u8 fifo_space = xiic_tx_fifo_space(priv);
144 int len = msg->len;
145 u32 pos = 0;
146
147 len = (len > fifo_space) ? fifo_space : len;
148
149 while (len--) {
150 u16 data = msg->buf[pos++];
151
152 if (pos == len && nmsgs == 1) {
153 /* last message in transfer -> STOP */
154 data |= XIIC_TX_DYN_STOP_MASK;
155 }
156 writew(data, priv->base + XIIC_DTR_REG_OFFSET);
157 }
158 }
159
xilinx_xiic_set_addr(struct udevice * dev,u8 addr,u16 flags,u32 len,u32 nmsgs)160 static void xilinx_xiic_set_addr(struct udevice *dev, u8 addr,
161 u16 flags, u32 len, u32 nmsgs)
162 {
163 struct xilinx_xiic_priv *priv = dev_get_priv(dev);
164
165 xiic_irq_clr(priv, XIIC_INTR_TX_ERROR_MASK);
166
167 if (!(flags & I2C_M_NOSTART)) {
168 /* write the address */
169 u16 data = i2c_8bit_addr_from_flags(addr, flags) |
170 XIIC_TX_DYN_START_MASK;
171 if (nmsgs == 1 && len == 0)
172 /* no data and last message -> add STOP */
173 data |= XIIC_TX_DYN_STOP_MASK;
174
175 writew(data, priv->base + XIIC_DTR_REG_OFFSET);
176 }
177 }
178
xilinx_xiic_read_common(struct udevice * dev,struct i2c_msg * msg,u32 nmsgs)179 static int xilinx_xiic_read_common(struct udevice *dev, struct i2c_msg *msg,
180 u32 nmsgs)
181 {
182 struct xilinx_xiic_priv *priv = dev_get_priv(dev);
183 u8 rx_watermark;
184
185 /* Clear and enable Rx full interrupt. */
186 xiic_irq_clr(priv, XIIC_INTR_RX_FULL_MASK | XIIC_INTR_TX_ERROR_MASK);
187
188 /* we want to get all but last byte, because the TX_ERROR IRQ is used
189 * to inidicate error ACK on the address, and negative ack on the last
190 * received byte, so to not mix them receive all but last.
191 * In the case where there is only one byte to receive
192 * we can check if ERROR and RX full is set at the same time
193 */
194 rx_watermark = msg->len;
195 if (rx_watermark > IIC_RX_FIFO_DEPTH)
196 rx_watermark = IIC_RX_FIFO_DEPTH;
197
198 writeb(rx_watermark - 1, priv->base + XIIC_RFD_REG_OFFSET);
199
200 xilinx_xiic_set_addr(dev, msg->addr, msg->flags, msg->len, nmsgs);
201
202 xiic_irq_clr(priv, XIIC_INTR_BNB_MASK);
203
204 writew((msg->len & 0xff) | ((nmsgs == 1) ? XIIC_TX_DYN_STOP_MASK : 0),
205 priv->base + XIIC_DTR_REG_OFFSET);
206
207 if (nmsgs == 1)
208 /* very last, enable bus not busy as well */
209 xiic_irq_clr(priv, XIIC_INTR_BNB_MASK);
210
211 return xiic_read_rx(priv, msg, nmsgs);
212 }
213
xilinx_xiic_write_common(struct udevice * dev,struct i2c_msg * msg,int nmsgs)214 static int xilinx_xiic_write_common(struct udevice *dev, struct i2c_msg *msg,
215 int nmsgs)
216 {
217 struct xilinx_xiic_priv *priv = dev_get_priv(dev);
218 int ret;
219
220 xilinx_xiic_set_addr(dev, msg->addr, msg->flags, msg->len, nmsgs);
221 xiic_fill_tx_fifo(priv, msg, nmsgs);
222
223 ret = wait_for_bit_8(priv->base + XIIC_SR_REG_OFFSET,
224 XIIC_SR_TX_FIFO_EMPTY_MASK, false, 1000, true);
225 if (ret)
226 return ret;
227
228 /* Clear any pending Tx empty, Tx Error and then enable them. */
229 xiic_irq_clr(priv, XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_ERROR_MASK |
230 XIIC_INTR_BNB_MASK);
231
232 return 0;
233 }
234
xiic_clear_rx_fifo(struct xilinx_xiic_priv * priv)235 static void xiic_clear_rx_fifo(struct xilinx_xiic_priv *priv)
236 {
237 u8 sr;
238
239 for (sr = readb(priv->base + XIIC_SR_REG_OFFSET);
240 !(sr & XIIC_SR_RX_FIFO_EMPTY_MASK);
241 sr = readb(priv->base + XIIC_SR_REG_OFFSET))
242 readb(priv->base + XIIC_DRR_REG_OFFSET);
243 }
244
xiic_reinit(struct xilinx_xiic_priv * priv)245 static void xiic_reinit(struct xilinx_xiic_priv *priv)
246 {
247 writel(XIIC_RESET_MASK, priv->base + XIIC_RESETR_OFFSET);
248
249 /* Set receive Fifo depth to maximum (zero based). */
250 writeb(IIC_RX_FIFO_DEPTH - 1, priv->base + XIIC_RFD_REG_OFFSET);
251
252 /* Reset Tx Fifo. */
253 writeb(XIIC_CR_TX_FIFO_RESET_MASK, priv->base + XIIC_CR_REG_OFFSET);
254
255 /* Enable IIC Device, remove Tx Fifo reset & disable general call. */
256 writeb(XIIC_CR_ENABLE_DEVICE_MASK, priv->base + XIIC_CR_REG_OFFSET);
257
258 /* make sure RX fifo is empty */
259 xiic_clear_rx_fifo(priv);
260
261 /* Disable interrupts */
262 writel(0, priv->base + XIIC_DGIER_OFFSET);
263
264 xiic_irq_clr(priv, XIIC_INTR_ARB_LOST_MASK);
265 }
266
xilinx_xiic_xfer(struct udevice * dev,struct i2c_msg * msg,int nmsgs)267 static int xilinx_xiic_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
268 {
269 int ret = 0;
270
271 for (; nmsgs > 0; nmsgs--, msg++) {
272 if (msg->flags & I2C_M_RD)
273 ret = xilinx_xiic_read_common(dev, msg, nmsgs);
274 else
275 ret = xilinx_xiic_write_common(dev, msg, nmsgs);
276
277 if (ret)
278 return -EREMOTEIO;
279 }
280
281 return ret;
282 }
283
xilinx_xiic_probe_chip(struct udevice * dev,uint addr,uint flags)284 static int xilinx_xiic_probe_chip(struct udevice *dev, uint addr, uint flags)
285 {
286 struct xilinx_xiic_priv *priv = dev_get_priv(dev);
287 u32 reg;
288 int ret;
289
290 xiic_reinit(priv);
291
292 xilinx_xiic_set_addr(dev, addr, 0, 0, 1);
293 ret = wait_for_bit_8(priv->base + XIIC_SR_REG_OFFSET,
294 XIIC_SR_BUS_BUSY_MASK, false, 1000, true);
295 if (ret)
296 return ret;
297
298 reg = readl(priv->base + XIIC_IISR_OFFSET);
299 if (reg & XIIC_INTR_TX_ERROR_MASK)
300 return -ENODEV;
301
302 return 0;
303 }
304
xilinx_xiic_set_speed(struct udevice * dev,uint speed)305 static int xilinx_xiic_set_speed(struct udevice *dev, uint speed)
306 {
307 return 0;
308 }
309
xilinx_xiic_probe(struct udevice * dev)310 static int xilinx_xiic_probe(struct udevice *dev)
311 {
312 struct xilinx_xiic_priv *priv = dev_get_priv(dev);
313
314 priv->base = dev_read_addr_ptr(dev);
315
316 writel(XIIC_CR_TX_FIFO_RESET_MASK, priv->base + XIIC_CR_REG_OFFSET);
317 xiic_reinit(priv);
318
319 return 0;
320 }
321
322 static const struct dm_i2c_ops xilinx_xiic_ops = {
323 .xfer = xilinx_xiic_xfer,
324 .probe_chip = xilinx_xiic_probe_chip,
325 .set_bus_speed = xilinx_xiic_set_speed,
326 };
327
328 static const struct udevice_id xilinx_xiic_ids[] = {
329 { .compatible = "xlnx,xps-iic-2.00.a" },
330 { }
331 };
332
333 U_BOOT_DRIVER(xilinx_xiic) = {
334 .name = "xilinx_axi_i2c",
335 .id = UCLASS_I2C,
336 .of_match = xilinx_xiic_ids,
337 .probe = xilinx_xiic_probe,
338 .priv_auto_alloc_size = sizeof(struct xilinx_xiic_priv),
339 .ops = &xilinx_xiic_ops,
340 };
341