1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Intel Keem Bay eMMC PHY driver
4 * Copyright (C) 2020 Intel Corporation
5 */
6
7 #include <linux/bitfield.h>
8 #include <linux/clk.h>
9 #include <linux/delay.h>
10 #include <linux/mfd/syscon.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/of_address.h>
14 #include <linux/phy/phy.h>
15 #include <linux/platform_device.h>
16 #include <linux/regmap.h>
17
18 /* eMMC/SD/SDIO core/phy configuration registers */
19 #define PHY_CFG_0 0x24
20 #define SEL_DLY_TXCLK_MASK BIT(29)
21 #define OTAP_DLY_ENA_MASK BIT(27)
22 #define OTAP_DLY_SEL_MASK GENMASK(26, 23)
23 #define DLL_EN_MASK BIT(10)
24 #define PWR_DOWN_MASK BIT(0)
25
26 #define PHY_CFG_2 0x2c
27 #define SEL_FREQ_MASK GENMASK(12, 10)
28
29 #define PHY_STAT 0x40
30 #define CAL_DONE_MASK BIT(6)
31 #define IS_CALDONE(x) ((x) & CAL_DONE_MASK)
32 #define DLL_RDY_MASK BIT(5)
33 #define IS_DLLRDY(x) ((x) & DLL_RDY_MASK)
34
35 /* From ACS_eMMC51_16nFFC_RO1100_Userguide_v1p0.pdf p17 */
36 #define FREQSEL_200M_170M 0x0
37 #define FREQSEL_170M_140M 0x1
38 #define FREQSEL_140M_110M 0x2
39 #define FREQSEL_110M_80M 0x3
40 #define FREQSEL_80M_50M 0x4
41
42 struct keembay_emmc_phy {
43 struct regmap *syscfg;
44 struct clk *emmcclk;
45 };
46
47 static const struct regmap_config keembay_regmap_config = {
48 .reg_bits = 32,
49 .val_bits = 32,
50 .reg_stride = 4,
51 };
52
keembay_emmc_phy_power(struct phy * phy,bool on_off)53 static int keembay_emmc_phy_power(struct phy *phy, bool on_off)
54 {
55 struct keembay_emmc_phy *priv = phy_get_drvdata(phy);
56 unsigned int caldone;
57 unsigned int dllrdy;
58 unsigned int freqsel;
59 unsigned int mhz;
60 int ret;
61
62 /*
63 * Keep phyctrl_pdb and phyctrl_endll low to allow
64 * initialization of CALIO state M/C DFFs
65 */
66 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, PWR_DOWN_MASK,
67 FIELD_PREP(PWR_DOWN_MASK, 0));
68 if (ret) {
69 dev_err(&phy->dev, "CALIO power down bar failed: %d\n", ret);
70 return ret;
71 }
72
73 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, DLL_EN_MASK,
74 FIELD_PREP(DLL_EN_MASK, 0));
75 if (ret) {
76 dev_err(&phy->dev, "turn off the dll failed: %d\n", ret);
77 return ret;
78 }
79
80 /* Already finish power off above */
81 if (!on_off)
82 return 0;
83
84 mhz = DIV_ROUND_CLOSEST(clk_get_rate(priv->emmcclk), 1000000);
85 if (mhz <= 200 && mhz >= 170)
86 freqsel = FREQSEL_200M_170M;
87 else if (mhz <= 170 && mhz >= 140)
88 freqsel = FREQSEL_170M_140M;
89 else if (mhz <= 140 && mhz >= 110)
90 freqsel = FREQSEL_140M_110M;
91 else if (mhz <= 110 && mhz >= 80)
92 freqsel = FREQSEL_110M_80M;
93 else if (mhz <= 80 && mhz >= 50)
94 freqsel = FREQSEL_80M_50M;
95 else
96 freqsel = 0x0;
97
98 if (mhz < 50 || mhz > 200)
99 dev_warn(&phy->dev, "Unsupported rate: %d MHz\n", mhz);
100
101 /*
102 * According to the user manual, calpad calibration
103 * cycle takes more than 2us without the minimal recommended
104 * value, so we may need a little margin here
105 */
106 udelay(5);
107
108 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, PWR_DOWN_MASK,
109 FIELD_PREP(PWR_DOWN_MASK, 1));
110 if (ret) {
111 dev_err(&phy->dev, "CALIO power down bar failed: %d\n", ret);
112 return ret;
113 }
114
115 /*
116 * According to the user manual, it asks driver to wait 5us for
117 * calpad busy trimming. However it is documented that this value is
118 * PVT(A.K.A. process, voltage and temperature) relevant, so some
119 * failure cases are found which indicates we should be more tolerant
120 * to calpad busy trimming.
121 */
122 ret = regmap_read_poll_timeout(priv->syscfg, PHY_STAT,
123 caldone, IS_CALDONE(caldone),
124 0, 50);
125 if (ret) {
126 dev_err(&phy->dev, "caldone failed, ret=%d\n", ret);
127 return ret;
128 }
129
130 /* Set the frequency of the DLL operation */
131 ret = regmap_update_bits(priv->syscfg, PHY_CFG_2, SEL_FREQ_MASK,
132 FIELD_PREP(SEL_FREQ_MASK, freqsel));
133 if (ret) {
134 dev_err(&phy->dev, "set the frequency of dll failed:%d\n", ret);
135 return ret;
136 }
137
138 /* Turn on the DLL */
139 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, DLL_EN_MASK,
140 FIELD_PREP(DLL_EN_MASK, 1));
141 if (ret) {
142 dev_err(&phy->dev, "turn on the dll failed: %d\n", ret);
143 return ret;
144 }
145
146 /*
147 * We turned on the DLL even though the rate was 0 because we the
148 * clock might be turned on later. ...but we can't wait for the DLL
149 * to lock when the rate is 0 because it will never lock with no
150 * input clock.
151 *
152 * Technically we should be checking the lock later when the clock
153 * is turned on, but for now we won't.
154 */
155 if (mhz == 0)
156 return 0;
157
158 /*
159 * After enabling analog DLL circuits docs say that we need 10.2 us if
160 * our source clock is at 50 MHz and that lock time scales linearly
161 * with clock speed. If we are powering on the PHY and the card clock
162 * is super slow (like 100kHz) this could take as long as 5.1 ms as
163 * per the math: 10.2 us * (50000000 Hz / 100000 Hz) => 5.1 ms
164 * hopefully we won't be running at 100 kHz, but we should still make
165 * sure we wait long enough.
166 *
167 * NOTE: There appear to be corner cases where the DLL seems to take
168 * extra long to lock for reasons that aren't understood. In some
169 * extreme cases we've seen it take up to over 10ms (!). We'll be
170 * generous and give it 50ms.
171 */
172 ret = regmap_read_poll_timeout(priv->syscfg, PHY_STAT,
173 dllrdy, IS_DLLRDY(dllrdy),
174 0, 50 * USEC_PER_MSEC);
175 if (ret)
176 dev_err(&phy->dev, "dllrdy failed, ret=%d\n", ret);
177
178 return ret;
179 }
180
keembay_emmc_phy_init(struct phy * phy)181 static int keembay_emmc_phy_init(struct phy *phy)
182 {
183 struct keembay_emmc_phy *priv = phy_get_drvdata(phy);
184
185 /*
186 * We purposely get the clock here and not in probe to avoid the
187 * circular dependency problem. We expect:
188 * - PHY driver to probe
189 * - SDHCI driver to start probe
190 * - SDHCI driver to register it's clock
191 * - SDHCI driver to get the PHY
192 * - SDHCI driver to init the PHY
193 *
194 * The clock is optional, so upon any error just return it like
195 * any other error to user.
196 */
197 priv->emmcclk = clk_get_optional(&phy->dev, "emmcclk");
198
199 return PTR_ERR_OR_ZERO(priv->emmcclk);
200 }
201
keembay_emmc_phy_exit(struct phy * phy)202 static int keembay_emmc_phy_exit(struct phy *phy)
203 {
204 struct keembay_emmc_phy *priv = phy_get_drvdata(phy);
205
206 clk_put(priv->emmcclk);
207
208 return 0;
209 };
210
keembay_emmc_phy_power_on(struct phy * phy)211 static int keembay_emmc_phy_power_on(struct phy *phy)
212 {
213 struct keembay_emmc_phy *priv = phy_get_drvdata(phy);
214 int ret;
215
216 /* Delay chain based txclk: enable */
217 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, SEL_DLY_TXCLK_MASK,
218 FIELD_PREP(SEL_DLY_TXCLK_MASK, 1));
219 if (ret) {
220 dev_err(&phy->dev, "ERROR: delay chain txclk set: %d\n", ret);
221 return ret;
222 }
223
224 /* Output tap delay: enable */
225 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, OTAP_DLY_ENA_MASK,
226 FIELD_PREP(OTAP_DLY_ENA_MASK, 1));
227 if (ret) {
228 dev_err(&phy->dev, "ERROR: output tap delay set: %d\n", ret);
229 return ret;
230 }
231
232 /* Output tap delay */
233 ret = regmap_update_bits(priv->syscfg, PHY_CFG_0, OTAP_DLY_SEL_MASK,
234 FIELD_PREP(OTAP_DLY_SEL_MASK, 2));
235 if (ret) {
236 dev_err(&phy->dev, "ERROR: output tap delay select: %d\n", ret);
237 return ret;
238 }
239
240 /* Power up eMMC phy analog blocks */
241 return keembay_emmc_phy_power(phy, true);
242 }
243
keembay_emmc_phy_power_off(struct phy * phy)244 static int keembay_emmc_phy_power_off(struct phy *phy)
245 {
246 /* Power down eMMC phy analog blocks */
247 return keembay_emmc_phy_power(phy, false);
248 }
249
250 static const struct phy_ops ops = {
251 .init = keembay_emmc_phy_init,
252 .exit = keembay_emmc_phy_exit,
253 .power_on = keembay_emmc_phy_power_on,
254 .power_off = keembay_emmc_phy_power_off,
255 .owner = THIS_MODULE,
256 };
257
keembay_emmc_phy_probe(struct platform_device * pdev)258 static int keembay_emmc_phy_probe(struct platform_device *pdev)
259 {
260 struct device *dev = &pdev->dev;
261 struct device_node *np = dev->of_node;
262 struct keembay_emmc_phy *priv;
263 struct phy *generic_phy;
264 struct phy_provider *phy_provider;
265 void __iomem *base;
266
267 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
268 if (!priv)
269 return -ENOMEM;
270
271 base = devm_platform_ioremap_resource(pdev, 0);
272 if (IS_ERR(base))
273 return PTR_ERR(base);
274
275 priv->syscfg = devm_regmap_init_mmio(dev, base, &keembay_regmap_config);
276 if (IS_ERR(priv->syscfg))
277 return PTR_ERR(priv->syscfg);
278
279 generic_phy = devm_phy_create(dev, np, &ops);
280 if (IS_ERR(generic_phy))
281 return dev_err_probe(dev, PTR_ERR(generic_phy),
282 "failed to create PHY\n");
283
284 phy_set_drvdata(generic_phy, priv);
285 phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
286
287 return PTR_ERR_OR_ZERO(phy_provider);
288 }
289
290 static const struct of_device_id keembay_emmc_phy_dt_ids[] = {
291 { .compatible = "intel,keembay-emmc-phy" },
292 {}
293 };
294 MODULE_DEVICE_TABLE(of, keembay_emmc_phy_dt_ids);
295
296 static struct platform_driver keembay_emmc_phy_driver = {
297 .probe = keembay_emmc_phy_probe,
298 .driver = {
299 .name = "keembay-emmc-phy",
300 .of_match_table = keembay_emmc_phy_dt_ids,
301 },
302 };
303 module_platform_driver(keembay_emmc_phy_driver);
304
305 MODULE_AUTHOR("Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>");
306 MODULE_DESCRIPTION("Intel Keem Bay eMMC PHY driver");
307 MODULE_LICENSE("GPL v2");
308