drivers/gpio/gpio-stp-xway.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  *  Copyright (C) 2012 John Crispin <john@phrozen.org>
   5  */
   6
   7 #include <linux/slab.h>
   8 #include <linux/init.h>
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/of_platform.h>
  12 #include <linux/mutex.h>
  13 #include <linux/gpio/driver.h>
  14 #include <linux/io.h>
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17
  18 /*
  19  * The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
  20  * peripheral controller used to drive external shift register cascades. At most
  21  * 3 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
  22  * to drive the 2 LSBs of the cascade automatically.
  23  */
  24
  25 /* control register 0 */
  26 #define XWAY_STP_CON0           0x00
  27 /* control register 1 */
  28 #define XWAY_STP_CON1           0x04
  29 /* data register 0 */
  30 #define XWAY_STP_CPU0           0x08
  31 /* data register 1 */
  32 #define XWAY_STP_CPU1           0x0C
  33 /* access register */
  34 #define XWAY_STP_AR             0x10
  35
  36 /* software or hardware update select bit */
  37 #define XWAY_STP_CON_SWU        BIT(31)
  38
  39 /* automatic update rates */
  40 #define XWAY_STP_2HZ            0
  41 #define XWAY_STP_4HZ            BIT(23)
  42 #define XWAY_STP_8HZ            BIT(24)
  43 #define XWAY_STP_10HZ           (BIT(24) | BIT(23))
  44 #define XWAY_STP_SPEED_MASK     (BIT(23) | BIT(24) | BIT(25) | BIT(26) | BIT(27))
  45
  46 #define XWAY_STP_FPIS_VALUE     BIT(21)
  47 #define XWAY_STP_FPIS_MASK      (BIT(20) | BIT(21))
  48
  49 /* clock source for automatic update */
  50 #define XWAY_STP_UPD_FPI        BIT(31)
  51 #define XWAY_STP_UPD_MASK       (BIT(31) | BIT(30))
  52
  53 /* let the adsl core drive the 2 LSBs */
  54 #define XWAY_STP_ADSL_SHIFT     24
  55 #define XWAY_STP_ADSL_MASK      0x3
  56
  57 /* 2 groups of 3 bits can be driven by the phys */
  58 #define XWAY_STP_PHY_MASK       0x7
  59 #define XWAY_STP_PHY1_SHIFT     27
  60 #define XWAY_STP_PHY2_SHIFT     3
  61 #define XWAY_STP_PHY3_SHIFT     6
  62 #define XWAY_STP_PHY4_SHIFT     15
  63
  64 /* STP has 3 groups of 8 bits */
  65 #define XWAY_STP_GROUP0         BIT(0)
  66 #define XWAY_STP_GROUP1         BIT(1)
  67 #define XWAY_STP_GROUP2         BIT(2)
  68 #define XWAY_STP_GROUP_MASK     (0x7)
  69
  70 /* Edge configuration bits */
  71 #define XWAY_STP_FALLING        BIT(26)
  72 #define XWAY_STP_EDGE_MASK      BIT(26)
  73
  74 #define xway_stp_r32(m, reg)            __raw_readl(m + reg)
  75 #define xway_stp_w32(m, val, reg)       __raw_writel(val, m + reg)
  76 #define xway_stp_w32_mask(m, clear, set, reg) \
  77                 xway_stp_w32(m, (xway_stp_r32(m, reg) & ~(clear)) | (set), reg)
  78
  79 struct xway_stp {
  80         struct gpio_chip gc;
  81         void __iomem *virt;
  82         u32 edge;       /* rising or falling edge triggered shift register */
  83         u32 shadow;     /* shadow the shift registers state */
  84         u8 groups;      /* we can drive 1-3 groups of 8bit each */
  85         u8 dsl;         /* the 2 LSBs can be driven by the dsl core */
  86         u8 phy1;        /* 3 bits can be driven by phy1 */
  87         u8 phy2;        /* 3 bits can be driven by phy2 */
  88         u8 phy3;        /* 3 bits can be driven by phy3 */
  89         u8 phy4;        /* 3 bits can be driven by phy4 */
  90         u8 reserved;    /* mask out the hw driven bits in gpio_request */
  91 };
  92
  93 /**
  94  * xway_stp_get() - gpio_chip->get - get gpios.
  95  * @gc:     Pointer to gpio_chip device structure.
  96  * @gpio:   GPIO signal number.
  97  *
  98  * Gets the shadow value.
  99  */
 100 static int xway_stp_get(struct gpio_chip *gc, unsigned int gpio)
 101 {
 102         struct xway_stp *chip = gpiochip_get_data(gc);
 103
 104         return (xway_stp_r32(chip->virt, XWAY_STP_CPU0) & BIT(gpio));
 105 }
 106
 107 /**
 108  * xway_stp_set() - gpio_chip->set - set gpios.
 109  * @gc:     Pointer to gpio_chip device structure.
 110  * @gpio:   GPIO signal number.
 111  * @val:    Value to be written to specified signal.
 112  *
 113  * Set the shadow value and call ltq_ebu_apply.
 114  */
 115 static void xway_stp_set(struct gpio_chip *gc, unsigned gpio, int val)
 116 {
 117         struct xway_stp *chip = gpiochip_get_data(gc);
 118
 119         if (val)
 120                 chip->shadow |= BIT(gpio);
 121         else
 122                 chip->shadow &= ~BIT(gpio);
 123         xway_stp_w32(chip->virt, chip->shadow, XWAY_STP_CPU0);
 124         if (!chip->reserved)
 125                 xway_stp_w32_mask(chip->virt, 0, XWAY_STP_CON_SWU, XWAY_STP_CON0);
 126 }
 127
 128 /**
 129  * xway_stp_dir_out() - gpio_chip->dir_out - set gpio direction.
 130  * @gc:     Pointer to gpio_chip device structure.
 131  * @gpio:   GPIO signal number.
 132  * @val:    Value to be written to specified signal.
 133  *
 134  * Same as xway_stp_set, always returns 0.
 135  */
 136 static int xway_stp_dir_out(struct gpio_chip *gc, unsigned gpio, int val)
 137 {
 138         xway_stp_set(gc, gpio, val);
 139
 140         return 0;
 141 }
 142
 143 /**
 144  * xway_stp_request() - gpio_chip->request
 145  * @gc:     Pointer to gpio_chip device structure.
 146  * @gpio:   GPIO signal number.
 147  *
 148  * We mask out the HW driven pins
 149  */
 150 static int xway_stp_request(struct gpio_chip *gc, unsigned gpio)
 151 {
 152         struct xway_stp *chip = gpiochip_get_data(gc);
 153
 154         if ((gpio < 8) && (chip->reserved & BIT(gpio))) {
 155                 dev_err(gc->parent, "GPIO %d is driven by hardware\n", gpio);
 156                 return -ENODEV;
 157         }
 158
 159         return 0;
 160 }
 161
 162 /**
 163  * xway_stp_hw_init() - Configure the STP unit and enable the clock gate
 164  * @chip: Pointer to the xway_stp chip structure
 165  */
 166 static void xway_stp_hw_init(struct xway_stp *chip)
 167 {
 168         /* sane defaults */
 169         xway_stp_w32(chip->virt, 0, XWAY_STP_AR);
 170         xway_stp_w32(chip->virt, 0, XWAY_STP_CPU0);
 171         xway_stp_w32(chip->virt, 0, XWAY_STP_CPU1);
 172         xway_stp_w32(chip->virt, XWAY_STP_CON_SWU, XWAY_STP_CON0);
 173         xway_stp_w32(chip->virt, 0, XWAY_STP_CON1);
 174
 175         /* apply edge trigger settings for the shift register */
 176         xway_stp_w32_mask(chip->virt, XWAY_STP_EDGE_MASK,
 177                                 chip->edge, XWAY_STP_CON0);
 178
 179         /* apply led group settings */
 180         xway_stp_w32_mask(chip->virt, XWAY_STP_GROUP_MASK,
 181                                 chip->groups, XWAY_STP_CON1);
 182
 183         /* tell the hardware which pins are controlled by the dsl modem */
 184         xway_stp_w32_mask(chip->virt,
 185                         XWAY_STP_ADSL_MASK << XWAY_STP_ADSL_SHIFT,
 186                         chip->dsl << XWAY_STP_ADSL_SHIFT,
 187                         XWAY_STP_CON0);
 188
 189         /* tell the hardware which pins are controlled by the phys */
 190         xway_stp_w32_mask(chip->virt,
 191                         XWAY_STP_PHY_MASK << XWAY_STP_PHY1_SHIFT,
 192                         chip->phy1 << XWAY_STP_PHY1_SHIFT,
 193                         XWAY_STP_CON0);
 194         xway_stp_w32_mask(chip->virt,
 195                         XWAY_STP_PHY_MASK << XWAY_STP_PHY2_SHIFT,
 196                         chip->phy2 << XWAY_STP_PHY2_SHIFT,
 197                         XWAY_STP_CON1);
 198
 199         if (of_machine_is_compatible("lantiq,grx390")
 200             || of_machine_is_compatible("lantiq,ar10")) {
 201                 xway_stp_w32_mask(chip->virt,
 202                                 XWAY_STP_PHY_MASK << XWAY_STP_PHY3_SHIFT,
 203                                 chip->phy3 << XWAY_STP_PHY3_SHIFT,
 204                                 XWAY_STP_CON1);
 205         }
 206
 207         if (of_machine_is_compatible("lantiq,grx390")) {
 208                 xway_stp_w32_mask(chip->virt,
 209                                 XWAY_STP_PHY_MASK << XWAY_STP_PHY4_SHIFT,
 210                                 chip->phy4 << XWAY_STP_PHY4_SHIFT,
 211                                 XWAY_STP_CON1);
 212         }
 213
 214         /* mask out the hw driven bits in gpio_request */
 215         chip->reserved = (chip->phy4 << 11) | (chip->phy3 << 8) | (chip->phy2 << 5)
 216                 | (chip->phy1 << 2) | chip->dsl;
 217
 218         /*
 219          * if we have pins that are driven by hw, we need to tell the stp what
 220          * clock to use as a timer.
 221          */
 222         if (chip->reserved) {
 223                 xway_stp_w32_mask(chip->virt, XWAY_STP_UPD_MASK,
 224                         XWAY_STP_UPD_FPI, XWAY_STP_CON1);
 225                 xway_stp_w32_mask(chip->virt, XWAY_STP_SPEED_MASK,
 226                         XWAY_STP_10HZ, XWAY_STP_CON1);
 227                 xway_stp_w32_mask(chip->virt, XWAY_STP_FPIS_MASK,
 228                         XWAY_STP_FPIS_VALUE, XWAY_STP_CON1);
 229         }
 230 }
 231
 232 static int xway_stp_probe(struct platform_device *pdev)
 233 {
 234         u32 shadow, groups, dsl, phy;
 235         struct xway_stp *chip;
 236         struct clk *clk;
 237         int ret = 0;
 238
 239         chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
 240         if (!chip)
 241                 return -ENOMEM;
 242
 243         chip->virt = devm_platform_ioremap_resource(pdev, 0);
 244         if (IS_ERR(chip->virt))
 245                 return PTR_ERR(chip->virt);
 246
 247         chip->gc.parent = &pdev->dev;
 248         chip->gc.label = "stp-xway";
 249         chip->gc.direction_output = xway_stp_dir_out;
 250         chip->gc.get = xway_stp_get;
 251         chip->gc.set = xway_stp_set;
 252         chip->gc.request = xway_stp_request;
 253         chip->gc.base = -1;
 254         chip->gc.owner = THIS_MODULE;
 255
 256         /* store the shadow value if one was passed by the devicetree */
 257         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
 258                 chip->shadow = shadow;
 259
 260         /* find out which gpio groups should be enabled */
 261         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,groups", &groups))
 262                 chip->groups = groups & XWAY_STP_GROUP_MASK;
 263         else
 264                 chip->groups = XWAY_STP_GROUP0;
 265         chip->gc.ngpio = fls(chip->groups) * 8;
 266
 267         /* find out which gpios are controlled by the dsl core */
 268         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,dsl", &dsl))
 269                 chip->dsl = dsl & XWAY_STP_ADSL_MASK;
 270
 271         /* find out which gpios are controlled by the phys */
 272         if (of_machine_is_compatible("lantiq,ar9") ||
 273                         of_machine_is_compatible("lantiq,gr9") ||
 274                         of_machine_is_compatible("lantiq,vr9") ||
 275                         of_machine_is_compatible("lantiq,ar10") ||
 276                         of_machine_is_compatible("lantiq,grx390")) {
 277                 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,phy1", &phy))
 278                         chip->phy1 = phy & XWAY_STP_PHY_MASK;
 279                 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,phy2", &phy))
 280                         chip->phy2 = phy & XWAY_STP_PHY_MASK;
 281         }
 282
 283         if (of_machine_is_compatible("lantiq,ar10") ||
 284                         of_machine_is_compatible("lantiq,grx390")) {
 285                 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,phy3", &phy))
 286                         chip->phy3 = phy & XWAY_STP_PHY_MASK;
 287         }
 288
 289         if (of_machine_is_compatible("lantiq,grx390")) {
 290                 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,phy4", &phy))
 291                         chip->phy4 = phy & XWAY_STP_PHY_MASK;
 292         }
 293
 294         /* check which edge trigger we should use, default to a falling edge */
 295         if (!of_find_property(pdev->dev.of_node, "lantiq,rising", NULL))
 296                 chip->edge = XWAY_STP_FALLING;
 297
 298         clk = devm_clk_get(&pdev->dev, NULL);
 299         if (IS_ERR(clk)) {
 300                 dev_err(&pdev->dev, "Failed to get clock\n");
 301                 return PTR_ERR(clk);
 302         }
 303
 304         ret = clk_prepare_enable(clk);
 305         if (ret)
 306                 return ret;
 307
 308         xway_stp_hw_init(chip);
 309
 310         ret = devm_gpiochip_add_data(&pdev->dev, &chip->gc, chip);
 311         if (ret) {
 312                 clk_disable_unprepare(clk);
 313                 return ret;
 314         }
 315
 316         dev_info(&pdev->dev, "Init done\n");
 317
 318         return 0;
 319 }
 320
 321 static const struct of_device_id xway_stp_match[] = {
 322         { .compatible = "lantiq,gpio-stp-xway" },
 323         {},
 324 };
 325 MODULE_DEVICE_TABLE(of, xway_stp_match);
 326
 327 static struct platform_driver xway_stp_driver = {
 328         .probe = xway_stp_probe,
 329         .driver = {
 330                 .name = "gpio-stp-xway",
 331                 .of_match_table = xway_stp_match,
 332         },
 333 };
 334
 335 static int __init xway_stp_init(void)
 336 {
 337         return platform_driver_register(&xway_stp_driver);
 338 }
 339
 340 subsys_initcall(xway_stp_init);