1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2023 Code Construct
4  *
5  * Author: Jeremy Kerr <jk@codeconstruct.com.au>
6  */
7 
8 #include <linux/mfd/syscon.h>
9 #include <linux/module.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12 #include <linux/regmap.h>
13 
14 #include "dw-i3c-master.h"
15 
16 /* AST2600-specific global register set */
17 #define AST2600_I3CG_REG0(idx)	(((idx) * 4 * 4) + 0x10)
18 #define AST2600_I3CG_REG1(idx)	(((idx) * 4 * 4) + 0x14)
19 
20 #define AST2600_I3CG_REG0_SDA_PULLUP_EN_MASK	GENMASK(29, 28)
21 #define AST2600_I3CG_REG0_SDA_PULLUP_EN_2K	(0x0 << 28)
22 #define AST2600_I3CG_REG0_SDA_PULLUP_EN_750	(0x2 << 28)
23 #define AST2600_I3CG_REG0_SDA_PULLUP_EN_545	(0x3 << 28)
24 
25 #define AST2600_I3CG_REG1_I2C_MODE		BIT(0)
26 #define AST2600_I3CG_REG1_TEST_MODE		BIT(1)
27 #define AST2600_I3CG_REG1_ACT_MODE_MASK		GENMASK(3, 2)
28 #define AST2600_I3CG_REG1_ACT_MODE(x)		(((x) << 2) & AST2600_I3CG_REG1_ACT_MODE_MASK)
29 #define AST2600_I3CG_REG1_PENDING_INT_MASK	GENMASK(7, 4)
30 #define AST2600_I3CG_REG1_PENDING_INT(x)	(((x) << 4) & AST2600_I3CG_REG1_PENDING_INT_MASK)
31 #define AST2600_I3CG_REG1_SA_MASK		GENMASK(14, 8)
32 #define AST2600_I3CG_REG1_SA(x)			(((x) << 8) & AST2600_I3CG_REG1_SA_MASK)
33 #define AST2600_I3CG_REG1_SA_EN			BIT(15)
34 #define AST2600_I3CG_REG1_INST_ID_MASK		GENMASK(19, 16)
35 #define AST2600_I3CG_REG1_INST_ID(x)		(((x) << 16) & AST2600_I3CG_REG1_INST_ID_MASK)
36 
37 #define AST2600_DEFAULT_SDA_PULLUP_OHMS		2000
38 
39 #define DEV_ADDR_TABLE_IBI_PEC			BIT(11)
40 
41 struct ast2600_i3c {
42 	struct dw_i3c_master dw;
43 	struct regmap *global_regs;
44 	unsigned int global_idx;
45 	unsigned int sda_pullup;
46 };
47 
48 static struct ast2600_i3c *to_ast2600_i3c(struct dw_i3c_master *dw)
49 {
50 	return container_of(dw, struct ast2600_i3c, dw);
51 }
52 
53 static int ast2600_i3c_pullup_to_reg(unsigned int ohms, u32 *regp)
54 {
55 	u32 reg;
56 
57 	switch (ohms) {
58 	case 2000:
59 		reg = AST2600_I3CG_REG0_SDA_PULLUP_EN_2K;
60 		break;
61 	case 750:
62 		reg = AST2600_I3CG_REG0_SDA_PULLUP_EN_750;
63 		break;
64 	case 545:
65 		reg = AST2600_I3CG_REG0_SDA_PULLUP_EN_545;
66 		break;
67 	default:
68 		return -EINVAL;
69 	}
70 
71 	if (regp)
72 		*regp = reg;
73 
74 	return 0;
75 }
76 
77 static int ast2600_i3c_init(struct dw_i3c_master *dw)
78 {
79 	struct ast2600_i3c *i3c = to_ast2600_i3c(dw);
80 	u32 reg = 0;
81 	int rc;
82 
83 	/* reg0: set SDA pullup values */
84 	rc = ast2600_i3c_pullup_to_reg(i3c->sda_pullup, &reg);
85 	if (rc)
86 		return rc;
87 
88 	rc = regmap_write(i3c->global_regs,
89 			  AST2600_I3CG_REG0(i3c->global_idx), reg);
90 	if (rc)
91 		return rc;
92 
93 	/* reg1: set up the instance id, but leave everything else disabled,
94 	 * as it's all for client mode
95 	 */
96 	reg = AST2600_I3CG_REG1_INST_ID(i3c->global_idx);
97 	rc = regmap_write(i3c->global_regs,
98 			  AST2600_I3CG_REG1(i3c->global_idx), reg);
99 
100 	return rc;
101 }
102 
103 static void ast2600_i3c_set_dat_ibi(struct dw_i3c_master *i3c,
104 				    struct i3c_dev_desc *dev,
105 				    bool enable, u32 *dat)
106 {
107 	/*
108 	 * The ast2600 i3c controller will lock up on receiving 4n+1-byte IBIs
109 	 * if the PEC is disabled. We have no way to restrict the length of
110 	 * IBIs sent to the controller, so we need to unconditionally enable
111 	 * PEC checking, which means we drop a byte of payload data
112 	 */
113 	if (enable && dev->info.bcr & I3C_BCR_IBI_PAYLOAD) {
114 		dev_warn_once(&i3c->base.dev,
115 		      "Enabling PEC workaround. IBI payloads will be truncated\n");
116 		*dat |= DEV_ADDR_TABLE_IBI_PEC;
117 	}
118 }
119 
120 static const struct dw_i3c_platform_ops ast2600_i3c_ops = {
121 	.init = ast2600_i3c_init,
122 	.set_dat_ibi = ast2600_i3c_set_dat_ibi,
123 };
124 
125 static int ast2600_i3c_probe(struct platform_device *pdev)
126 {
127 	struct device_node *np = pdev->dev.of_node;
128 	struct of_phandle_args gspec;
129 	struct ast2600_i3c *i3c;
130 	int rc;
131 
132 	i3c = devm_kzalloc(&pdev->dev, sizeof(*i3c), GFP_KERNEL);
133 	if (!i3c)
134 		return -ENOMEM;
135 
136 	rc = of_parse_phandle_with_fixed_args(np, "aspeed,global-regs", 1, 0,
137 					      &gspec);
138 	if (rc)
139 		return -ENODEV;
140 
141 	i3c->global_regs = syscon_node_to_regmap(gspec.np);
142 	of_node_put(gspec.np);
143 
144 	if (IS_ERR(i3c->global_regs))
145 		return PTR_ERR(i3c->global_regs);
146 
147 	i3c->global_idx = gspec.args[0];
148 
149 	rc = of_property_read_u32(np, "sda-pullup-ohms", &i3c->sda_pullup);
150 	if (rc)
151 		i3c->sda_pullup = AST2600_DEFAULT_SDA_PULLUP_OHMS;
152 
153 	rc = ast2600_i3c_pullup_to_reg(i3c->sda_pullup, NULL);
154 	if (rc)
155 		dev_err(&pdev->dev, "invalid sda-pullup value %d\n",
156 			i3c->sda_pullup);
157 
158 	i3c->dw.platform_ops = &ast2600_i3c_ops;
159 	i3c->dw.ibi_capable = true;
160 	return dw_i3c_common_probe(&i3c->dw, pdev);
161 }
162 
163 static void ast2600_i3c_remove(struct platform_device *pdev)
164 {
165 	struct dw_i3c_master *dw_i3c = platform_get_drvdata(pdev);
166 
167 	dw_i3c_common_remove(dw_i3c);
168 }
169 
170 static const struct of_device_id ast2600_i3c_master_of_match[] = {
171 	{ .compatible = "aspeed,ast2600-i3c", },
172 	{},
173 };
174 MODULE_DEVICE_TABLE(of, ast2600_i3c_master_of_match);
175 
176 static struct platform_driver ast2600_i3c_driver = {
177 	.probe = ast2600_i3c_probe,
178 	.remove_new = ast2600_i3c_remove,
179 	.driver = {
180 		.name = "ast2600-i3c-master",
181 		.of_match_table = ast2600_i3c_master_of_match,
182 	},
183 };
184 module_platform_driver(ast2600_i3c_driver);
185 
186 MODULE_AUTHOR("Jeremy Kerr <jk@codeconstruct.com.au>");
187 MODULE_DESCRIPTION("ASPEED AST2600 I3C driver");
188 MODULE_LICENSE("GPL");
189