drivers/gpio/gpio-stp-xway.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify it
   3  *  under the terms of the GNU General Public License version 2 as published
   4  *  by the Free Software Foundation.
   5  *
   6  *  Copyright (C) 2012 John Crispin <john@phrozen.org>
   7  *
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/init.h>
  12 #include <linux/module.h>
  13 #include <linux/types.h>
  14 #include <linux/of_platform.h>
  15 #include <linux/mutex.h>
  16 #include <linux/gpio.h>
  17 #include <linux/io.h>
  18 #include <linux/of_gpio.h>
  19 #include <linux/clk.h>
  20 #include <linux/err.h>
  21
  22 #include <lantiq_soc.h>
  23
  24 /*
  25  * The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
  26  * peripheral controller used to drive external shift register cascades. At most
  27  * 3 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
  28  * to drive the 2 LSBs of the cascade automatically.
  29  */
  30
  31 /* control register 0 */
  32 #define XWAY_STP_CON0           0x00
  33 /* control register 1 */
  34 #define XWAY_STP_CON1           0x04
  35 /* data register 0 */
  36 #define XWAY_STP_CPU0           0x08
  37 /* data register 1 */
  38 #define XWAY_STP_CPU1           0x0C
  39 /* access register */
  40 #define XWAY_STP_AR             0x10
  41
  42 /* software or hardware update select bit */
  43 #define XWAY_STP_CON_SWU        BIT(31)
  44
  45 /* automatic update rates */
  46 #define XWAY_STP_2HZ            0
  47 #define XWAY_STP_4HZ            BIT(23)
  48 #define XWAY_STP_8HZ            BIT(24)
  49 #define XWAY_STP_10HZ           (BIT(24) | BIT(23))
  50 #define XWAY_STP_SPEED_MASK     (0xf << 23)
  51
  52 /* clock source for automatic update */
  53 #define XWAY_STP_UPD_FPI        BIT(31)
  54 #define XWAY_STP_UPD_MASK       (BIT(31) | BIT(30))
  55
  56 /* let the adsl core drive the 2 LSBs */
  57 #define XWAY_STP_ADSL_SHIFT     24
  58 #define XWAY_STP_ADSL_MASK      0x3
  59
  60 /* 2 groups of 3 bits can be driven by the phys */
  61 #define XWAY_STP_PHY_MASK       0x7
  62 #define XWAY_STP_PHY1_SHIFT     27
  63 #define XWAY_STP_PHY2_SHIFT     15
  64
  65 /* STP has 3 groups of 8 bits */
  66 #define XWAY_STP_GROUP0         BIT(0)
  67 #define XWAY_STP_GROUP1         BIT(1)
  68 #define XWAY_STP_GROUP2         BIT(2)
  69 #define XWAY_STP_GROUP_MASK     (0x7)
  70
  71 /* Edge configuration bits */
  72 #define XWAY_STP_FALLING        BIT(26)
  73 #define XWAY_STP_EDGE_MASK      BIT(26)
  74
  75 #define xway_stp_r32(m, reg)            __raw_readl(m + reg)
  76 #define xway_stp_w32(m, val, reg)       __raw_writel(val, m + reg)
  77 #define xway_stp_w32_mask(m, clear, set, reg) \
  78                 ltq_w32((ltq_r32(m + reg) & ~(clear)) | (set), \
  79                 m + reg)
  80
  81 struct xway_stp {
  82         struct gpio_chip gc;
  83         void __iomem *virt;
  84         u32 edge;       /* rising or falling edge triggered shift register */
  85         u32 shadow;     /* shadow the shift registers state */
  86         u8 groups;      /* we can drive 1-3 groups of 8bit each */
  87         u8 dsl;         /* the 2 LSBs can be driven by the dsl core */
  88         u8 phy1;        /* 3 bits can be driven by phy1 */
  89         u8 phy2;        /* 3 bits can be driven by phy2 */
  90         u8 reserved;    /* mask out the hw driven bits in gpio_request */
  91 };
  92
  93 /**
  94  * xway_stp_set() - gpio_chip->set - set gpios.
  95  * @gc:     Pointer to gpio_chip device structure.
  96  * @gpio:   GPIO signal number.
  97  * @val:    Value to be written to specified signal.
  98  *
  99  * Set the shadow value and call ltq_ebu_apply.
 100  */
 101 static void xway_stp_set(struct gpio_chip *gc, unsigned gpio, int val)
 102 {
 103         struct xway_stp *chip = gpiochip_get_data(gc);
 104
 105         if (val)
 106                 chip->shadow |= BIT(gpio);
 107         else
 108                 chip->shadow &= ~BIT(gpio);
 109         xway_stp_w32(chip->virt, chip->shadow, XWAY_STP_CPU0);
 110         xway_stp_w32_mask(chip->virt, 0, XWAY_STP_CON_SWU, XWAY_STP_CON0);
 111 }
 112
 113 /**
 114  * xway_stp_dir_out() - gpio_chip->dir_out - set gpio direction.
 115  * @gc:     Pointer to gpio_chip device structure.
 116  * @gpio:   GPIO signal number.
 117  * @val:    Value to be written to specified signal.
 118  *
 119  * Same as xway_stp_set, always returns 0.
 120  */
 121 static int xway_stp_dir_out(struct gpio_chip *gc, unsigned gpio, int val)
 122 {
 123         xway_stp_set(gc, gpio, val);
 124
 125         return 0;
 126 }
 127
 128 /**
 129  * xway_stp_request() - gpio_chip->request
 130  * @gc:     Pointer to gpio_chip device structure.
 131  * @gpio:   GPIO signal number.
 132  *
 133  * We mask out the HW driven pins
 134  */
 135 static int xway_stp_request(struct gpio_chip *gc, unsigned gpio)
 136 {
 137         struct xway_stp *chip = gpiochip_get_data(gc);
 138
 139         if ((gpio < 8) && (chip->reserved & BIT(gpio))) {
 140                 dev_err(gc->parent, "GPIO %d is driven by hardware\n", gpio);
 141                 return -ENODEV;
 142         }
 143
 144         return 0;
 145 }
 146
 147 /**
 148  * xway_stp_hw_init() - Configure the STP unit and enable the clock gate
 149  * @virt: pointer to the remapped register range
 150  */
 151 static int xway_stp_hw_init(struct xway_stp *chip)
 152 {
 153         /* sane defaults */
 154         xway_stp_w32(chip->virt, 0, XWAY_STP_AR);
 155         xway_stp_w32(chip->virt, 0, XWAY_STP_CPU0);
 156         xway_stp_w32(chip->virt, 0, XWAY_STP_CPU1);
 157         xway_stp_w32(chip->virt, XWAY_STP_CON_SWU, XWAY_STP_CON0);
 158         xway_stp_w32(chip->virt, 0, XWAY_STP_CON1);
 159
 160         /* apply edge trigger settings for the shift register */
 161         xway_stp_w32_mask(chip->virt, XWAY_STP_EDGE_MASK,
 162                                 chip->edge, XWAY_STP_CON0);
 163
 164         /* apply led group settings */
 165         xway_stp_w32_mask(chip->virt, XWAY_STP_GROUP_MASK,
 166                                 chip->groups, XWAY_STP_CON1);
 167
 168         /* tell the hardware which pins are controlled by the dsl modem */
 169         xway_stp_w32_mask(chip->virt,
 170                         XWAY_STP_ADSL_MASK << XWAY_STP_ADSL_SHIFT,
 171                         chip->dsl << XWAY_STP_ADSL_SHIFT,
 172                         XWAY_STP_CON0);
 173
 174         /* tell the hardware which pins are controlled by the phys */
 175         xway_stp_w32_mask(chip->virt,
 176                         XWAY_STP_PHY_MASK << XWAY_STP_PHY1_SHIFT,
 177                         chip->phy1 << XWAY_STP_PHY1_SHIFT,
 178                         XWAY_STP_CON0);
 179         xway_stp_w32_mask(chip->virt,
 180                         XWAY_STP_PHY_MASK << XWAY_STP_PHY2_SHIFT,
 181                         chip->phy2 << XWAY_STP_PHY2_SHIFT,
 182                         XWAY_STP_CON1);
 183
 184         /* mask out the hw driven bits in gpio_request */
 185         chip->reserved = (chip->phy2 << 5) | (chip->phy1 << 2) | chip->dsl;
 186
 187         /*
 188          * if we have pins that are driven by hw, we need to tell the stp what
 189          * clock to use as a timer.
 190          */
 191         if (chip->reserved)
 192                 xway_stp_w32_mask(chip->virt, XWAY_STP_UPD_MASK,
 193                         XWAY_STP_UPD_FPI, XWAY_STP_CON1);
 194
 195         return 0;
 196 }
 197
 198 static int xway_stp_probe(struct platform_device *pdev)
 199 {
 200         struct resource *res;
 201         u32 shadow, groups, dsl, phy;
 202         struct xway_stp *chip;
 203         struct clk *clk;
 204         int ret = 0;
 205
 206         chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
 207         if (!chip)
 208                 return -ENOMEM;
 209
 210         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 211         chip->virt = devm_ioremap_resource(&pdev->dev, res);
 212         if (IS_ERR(chip->virt))
 213                 return PTR_ERR(chip->virt);
 214
 215         chip->gc.parent = &pdev->dev;
 216         chip->gc.label = "stp-xway";
 217         chip->gc.direction_output = xway_stp_dir_out;
 218         chip->gc.set = xway_stp_set;
 219         chip->gc.request = xway_stp_request;
 220         chip->gc.base = -1;
 221         chip->gc.owner = THIS_MODULE;
 222
 223         /* store the shadow value if one was passed by the devicetree */
 224         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
 225                 chip->shadow = shadow;
 226
 227         /* find out which gpio groups should be enabled */
 228         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,groups", &groups))
 229                 chip->groups = groups & XWAY_STP_GROUP_MASK;
 230         else
 231                 chip->groups = XWAY_STP_GROUP0;
 232         chip->gc.ngpio = fls(chip->groups) * 8;
 233
 234         /* find out which gpios are controlled by the dsl core */
 235         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,dsl", &dsl))
 236                 chip->dsl = dsl & XWAY_STP_ADSL_MASK;
 237
 238         /* find out which gpios are controlled by the phys */
 239         if (of_machine_is_compatible("lantiq,ar9") ||
 240                         of_machine_is_compatible("lantiq,gr9") ||
 241                         of_machine_is_compatible("lantiq,vr9")) {
 242                 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,phy1", &phy))
 243                         chip->phy1 = phy & XWAY_STP_PHY_MASK;
 244                 if (!of_property_read_u32(pdev->dev.of_node, "lantiq,phy2", &phy))
 245                         chip->phy2 = phy & XWAY_STP_PHY_MASK;
 246         }
 247
 248         /* check which edge trigger we should use, default to a falling edge */
 249         if (!of_find_property(pdev->dev.of_node, "lantiq,rising", NULL))
 250                 chip->edge = XWAY_STP_FALLING;
 251
 252         clk = clk_get(&pdev->dev, NULL);
 253         if (IS_ERR(clk)) {
 254                 dev_err(&pdev->dev, "Failed to get clock\n");
 255                 return PTR_ERR(clk);
 256         }
 257         clk_enable(clk);
 258
 259         ret = xway_stp_hw_init(chip);
 260         if (!ret)
 261                 ret = devm_gpiochip_add_data(&pdev->dev, &chip->gc, chip);
 262
 263         if (!ret)
 264                 dev_info(&pdev->dev, "Init done\n");
 265
 266         return ret;
 267 }
 268
 269 static const struct of_device_id xway_stp_match[] = {
 270         { .compatible = "lantiq,gpio-stp-xway" },
 271         {},
 272 };
 273 MODULE_DEVICE_TABLE(of, xway_stp_match);
 274
 275 static struct platform_driver xway_stp_driver = {
 276         .probe = xway_stp_probe,
 277         .driver = {
 278                 .name = "gpio-stp-xway",
 279                 .of_match_table = xway_stp_match,
 280         },
 281 };
 282
 283 static int __init xway_stp_init(void)
 284 {
 285         return platform_driver_register(&xway_stp_driver);
 286 }
 287
 288 subsys_initcall(xway_stp_init);