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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 //
0003 // GPIO Aggregator
0004 //
0005 // Copyright (C) 2019-2020 Glider bv
0006 
0007 #define DRV_NAME       "gpio-aggregator"
0008 #define pr_fmt(fmt) DRV_NAME ": " fmt
0009 
0010 #include <linux/bitmap.h>
0011 #include <linux/bitops.h>
0012 #include <linux/ctype.h>
0013 #include <linux/gpio.h>
0014 #include <linux/gpio/consumer.h>
0015 #include <linux/gpio/driver.h>
0016 #include <linux/gpio/machine.h>
0017 #include <linux/idr.h>
0018 #include <linux/kernel.h>
0019 #include <linux/module.h>
0020 #include <linux/mutex.h>
0021 #include <linux/overflow.h>
0022 #include <linux/platform_device.h>
0023 #include <linux/spinlock.h>
0024 #include <linux/string.h>
0025 
0026 
0027 /*
0028  * GPIO Aggregator sysfs interface
0029  */
0030 
0031 struct gpio_aggregator {
0032     struct gpiod_lookup_table *lookups;
0033     struct platform_device *pdev;
0034     char args[];
0035 };
0036 
0037 static DEFINE_MUTEX(gpio_aggregator_lock);  /* protects idr */
0038 static DEFINE_IDR(gpio_aggregator_idr);
0039 
0040 static int aggr_add_gpio(struct gpio_aggregator *aggr, const char *key,
0041              int hwnum, unsigned int *n)
0042 {
0043     struct gpiod_lookup_table *lookups;
0044 
0045     lookups = krealloc(aggr->lookups, struct_size(lookups, table, *n + 2),
0046                GFP_KERNEL);
0047     if (!lookups)
0048         return -ENOMEM;
0049 
0050     lookups->table[*n] = GPIO_LOOKUP_IDX(key, hwnum, NULL, *n, 0);
0051 
0052     (*n)++;
0053     memset(&lookups->table[*n], 0, sizeof(lookups->table[*n]));
0054 
0055     aggr->lookups = lookups;
0056     return 0;
0057 }
0058 
0059 static int aggr_parse(struct gpio_aggregator *aggr)
0060 {
0061     char *args = skip_spaces(aggr->args);
0062     char *name, *offsets, *p;
0063     unsigned long *bitmap;
0064     unsigned int i, n = 0;
0065     int error = 0;
0066 
0067     bitmap = bitmap_alloc(ARCH_NR_GPIOS, GFP_KERNEL);
0068     if (!bitmap)
0069         return -ENOMEM;
0070 
0071     args = next_arg(args, &name, &p);
0072     while (*args) {
0073         args = next_arg(args, &offsets, &p);
0074 
0075         p = get_options(offsets, 0, &error);
0076         if (error == 0 || *p) {
0077             /* Named GPIO line */
0078             error = aggr_add_gpio(aggr, name, U16_MAX, &n);
0079             if (error)
0080                 goto free_bitmap;
0081 
0082             name = offsets;
0083             continue;
0084         }
0085 
0086         /* GPIO chip + offset(s) */
0087         error = bitmap_parselist(offsets, bitmap, ARCH_NR_GPIOS);
0088         if (error) {
0089             pr_err("Cannot parse %s: %d\n", offsets, error);
0090             goto free_bitmap;
0091         }
0092 
0093         for_each_set_bit(i, bitmap, ARCH_NR_GPIOS) {
0094             error = aggr_add_gpio(aggr, name, i, &n);
0095             if (error)
0096                 goto free_bitmap;
0097         }
0098 
0099         args = next_arg(args, &name, &p);
0100     }
0101 
0102     if (!n) {
0103         pr_err("No GPIOs specified\n");
0104         error = -EINVAL;
0105     }
0106 
0107 free_bitmap:
0108     bitmap_free(bitmap);
0109     return error;
0110 }
0111 
0112 static ssize_t new_device_store(struct device_driver *driver, const char *buf,
0113                 size_t count)
0114 {
0115     struct gpio_aggregator *aggr;
0116     struct platform_device *pdev;
0117     int res, id;
0118 
0119     /* kernfs guarantees string termination, so count + 1 is safe */
0120     aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
0121     if (!aggr)
0122         return -ENOMEM;
0123 
0124     memcpy(aggr->args, buf, count + 1);
0125 
0126     aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1),
0127                 GFP_KERNEL);
0128     if (!aggr->lookups) {
0129         res = -ENOMEM;
0130         goto free_ga;
0131     }
0132 
0133     mutex_lock(&gpio_aggregator_lock);
0134     id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
0135     mutex_unlock(&gpio_aggregator_lock);
0136 
0137     if (id < 0) {
0138         res = id;
0139         goto free_table;
0140     }
0141 
0142     aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
0143     if (!aggr->lookups->dev_id) {
0144         res = -ENOMEM;
0145         goto remove_idr;
0146     }
0147 
0148     res = aggr_parse(aggr);
0149     if (res)
0150         goto free_dev_id;
0151 
0152     gpiod_add_lookup_table(aggr->lookups);
0153 
0154     pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
0155     if (IS_ERR(pdev)) {
0156         res = PTR_ERR(pdev);
0157         goto remove_table;
0158     }
0159 
0160     aggr->pdev = pdev;
0161     return count;
0162 
0163 remove_table:
0164     gpiod_remove_lookup_table(aggr->lookups);
0165 free_dev_id:
0166     kfree(aggr->lookups->dev_id);
0167 remove_idr:
0168     mutex_lock(&gpio_aggregator_lock);
0169     idr_remove(&gpio_aggregator_idr, id);
0170     mutex_unlock(&gpio_aggregator_lock);
0171 free_table:
0172     kfree(aggr->lookups);
0173 free_ga:
0174     kfree(aggr);
0175     return res;
0176 }
0177 
0178 static DRIVER_ATTR_WO(new_device);
0179 
0180 static void gpio_aggregator_free(struct gpio_aggregator *aggr)
0181 {
0182     platform_device_unregister(aggr->pdev);
0183     gpiod_remove_lookup_table(aggr->lookups);
0184     kfree(aggr->lookups->dev_id);
0185     kfree(aggr->lookups);
0186     kfree(aggr);
0187 }
0188 
0189 static ssize_t delete_device_store(struct device_driver *driver,
0190                    const char *buf, size_t count)
0191 {
0192     struct gpio_aggregator *aggr;
0193     unsigned int id;
0194     int error;
0195 
0196     if (!str_has_prefix(buf, DRV_NAME "."))
0197         return -EINVAL;
0198 
0199     error = kstrtouint(buf + strlen(DRV_NAME "."), 10, &id);
0200     if (error)
0201         return error;
0202 
0203     mutex_lock(&gpio_aggregator_lock);
0204     aggr = idr_remove(&gpio_aggregator_idr, id);
0205     mutex_unlock(&gpio_aggregator_lock);
0206     if (!aggr)
0207         return -ENOENT;
0208 
0209     gpio_aggregator_free(aggr);
0210     return count;
0211 }
0212 static DRIVER_ATTR_WO(delete_device);
0213 
0214 static struct attribute *gpio_aggregator_attrs[] = {
0215     &driver_attr_new_device.attr,
0216     &driver_attr_delete_device.attr,
0217     NULL
0218 };
0219 ATTRIBUTE_GROUPS(gpio_aggregator);
0220 
0221 static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data)
0222 {
0223     gpio_aggregator_free(p);
0224     return 0;
0225 }
0226 
0227 static void __exit gpio_aggregator_remove_all(void)
0228 {
0229     mutex_lock(&gpio_aggregator_lock);
0230     idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
0231     idr_destroy(&gpio_aggregator_idr);
0232     mutex_unlock(&gpio_aggregator_lock);
0233 }
0234 
0235 
0236 /*
0237  *  GPIO Forwarder
0238  */
0239 
0240 struct gpiochip_fwd {
0241     struct gpio_chip chip;
0242     struct gpio_desc **descs;
0243     union {
0244         struct mutex mlock; /* protects tmp[] if can_sleep */
0245         spinlock_t slock;   /* protects tmp[] if !can_sleep */
0246     };
0247     unsigned long tmp[];        /* values and descs for multiple ops */
0248 };
0249 
0250 #define fwd_tmp_values(fwd) &(fwd)->tmp[0]
0251 #define fwd_tmp_descs(fwd)  (void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)]
0252 
0253 #define fwd_tmp_size(ngpios)    (BITS_TO_LONGS((ngpios)) + (ngpios))
0254 
0255 static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset)
0256 {
0257     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0258 
0259     return gpiod_get_direction(fwd->descs[offset]);
0260 }
0261 
0262 static int gpio_fwd_direction_input(struct gpio_chip *chip, unsigned int offset)
0263 {
0264     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0265 
0266     return gpiod_direction_input(fwd->descs[offset]);
0267 }
0268 
0269 static int gpio_fwd_direction_output(struct gpio_chip *chip,
0270                      unsigned int offset, int value)
0271 {
0272     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0273 
0274     return gpiod_direction_output(fwd->descs[offset], value);
0275 }
0276 
0277 static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset)
0278 {
0279     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0280 
0281     return chip->can_sleep ? gpiod_get_value_cansleep(fwd->descs[offset])
0282                    : gpiod_get_value(fwd->descs[offset]);
0283 }
0284 
0285 static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
0286                  unsigned long *bits)
0287 {
0288     struct gpio_desc **descs = fwd_tmp_descs(fwd);
0289     unsigned long *values = fwd_tmp_values(fwd);
0290     unsigned int i, j = 0;
0291     int error;
0292 
0293     bitmap_clear(values, 0, fwd->chip.ngpio);
0294     for_each_set_bit(i, mask, fwd->chip.ngpio)
0295         descs[j++] = fwd->descs[i];
0296 
0297     if (fwd->chip.can_sleep)
0298         error = gpiod_get_array_value_cansleep(j, descs, NULL, values);
0299     else
0300         error = gpiod_get_array_value(j, descs, NULL, values);
0301     if (error)
0302         return error;
0303 
0304     j = 0;
0305     for_each_set_bit(i, mask, fwd->chip.ngpio)
0306         __assign_bit(i, bits, test_bit(j++, values));
0307 
0308     return 0;
0309 }
0310 
0311 static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip,
0312                     unsigned long *mask, unsigned long *bits)
0313 {
0314     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0315     unsigned long flags;
0316     int error;
0317 
0318     if (chip->can_sleep) {
0319         mutex_lock(&fwd->mlock);
0320         error = gpio_fwd_get_multiple(fwd, mask, bits);
0321         mutex_unlock(&fwd->mlock);
0322     } else {
0323         spin_lock_irqsave(&fwd->slock, flags);
0324         error = gpio_fwd_get_multiple(fwd, mask, bits);
0325         spin_unlock_irqrestore(&fwd->slock, flags);
0326     }
0327 
0328     return error;
0329 }
0330 
0331 static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
0332 {
0333     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0334 
0335     if (chip->can_sleep)
0336         gpiod_set_value_cansleep(fwd->descs[offset], value);
0337     else
0338         gpiod_set_value(fwd->descs[offset], value);
0339 }
0340 
0341 static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
0342                   unsigned long *bits)
0343 {
0344     struct gpio_desc **descs = fwd_tmp_descs(fwd);
0345     unsigned long *values = fwd_tmp_values(fwd);
0346     unsigned int i, j = 0;
0347 
0348     for_each_set_bit(i, mask, fwd->chip.ngpio) {
0349         __assign_bit(j, values, test_bit(i, bits));
0350         descs[j++] = fwd->descs[i];
0351     }
0352 
0353     if (fwd->chip.can_sleep)
0354         gpiod_set_array_value_cansleep(j, descs, NULL, values);
0355     else
0356         gpiod_set_array_value(j, descs, NULL, values);
0357 }
0358 
0359 static void gpio_fwd_set_multiple_locked(struct gpio_chip *chip,
0360                      unsigned long *mask, unsigned long *bits)
0361 {
0362     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0363     unsigned long flags;
0364 
0365     if (chip->can_sleep) {
0366         mutex_lock(&fwd->mlock);
0367         gpio_fwd_set_multiple(fwd, mask, bits);
0368         mutex_unlock(&fwd->mlock);
0369     } else {
0370         spin_lock_irqsave(&fwd->slock, flags);
0371         gpio_fwd_set_multiple(fwd, mask, bits);
0372         spin_unlock_irqrestore(&fwd->slock, flags);
0373     }
0374 }
0375 
0376 static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
0377                    unsigned long config)
0378 {
0379     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0380 
0381     return gpiod_set_config(fwd->descs[offset], config);
0382 }
0383 
0384 static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
0385 {
0386     struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
0387 
0388     return gpiod_to_irq(fwd->descs[offset]);
0389 }
0390 
0391 /**
0392  * gpiochip_fwd_create() - Create a new GPIO forwarder
0393  * @dev: Parent device pointer
0394  * @ngpios: Number of GPIOs in the forwarder.
0395  * @descs: Array containing the GPIO descriptors to forward to.
0396  *         This array must contain @ngpios entries, and must not be deallocated
0397  *         before the forwarder has been destroyed again.
0398  *
0399  * This function creates a new gpiochip, which forwards all GPIO operations to
0400  * the passed GPIO descriptors.
0401  *
0402  * Return: An opaque object pointer, or an ERR_PTR()-encoded negative error
0403  *         code on failure.
0404  */
0405 static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
0406                         unsigned int ngpios,
0407                         struct gpio_desc *descs[])
0408 {
0409     const char *label = dev_name(dev);
0410     struct gpiochip_fwd *fwd;
0411     struct gpio_chip *chip;
0412     unsigned int i;
0413     int error;
0414 
0415     fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
0416                GFP_KERNEL);
0417     if (!fwd)
0418         return ERR_PTR(-ENOMEM);
0419 
0420     chip = &fwd->chip;
0421 
0422     /*
0423      * If any of the GPIO lines are sleeping, then the entire forwarder
0424      * will be sleeping.
0425      * If any of the chips support .set_config(), then the forwarder will
0426      * support setting configs.
0427      */
0428     for (i = 0; i < ngpios; i++) {
0429         struct gpio_chip *parent = gpiod_to_chip(descs[i]);
0430 
0431         dev_dbg(dev, "%u => gpio %d irq %d\n", i,
0432             desc_to_gpio(descs[i]), gpiod_to_irq(descs[i]));
0433 
0434         if (gpiod_cansleep(descs[i]))
0435             chip->can_sleep = true;
0436         if (parent && parent->set_config)
0437             chip->set_config = gpio_fwd_set_config;
0438     }
0439 
0440     chip->label = label;
0441     chip->parent = dev;
0442     chip->owner = THIS_MODULE;
0443     chip->get_direction = gpio_fwd_get_direction;
0444     chip->direction_input = gpio_fwd_direction_input;
0445     chip->direction_output = gpio_fwd_direction_output;
0446     chip->get = gpio_fwd_get;
0447     chip->get_multiple = gpio_fwd_get_multiple_locked;
0448     chip->set = gpio_fwd_set;
0449     chip->set_multiple = gpio_fwd_set_multiple_locked;
0450     chip->to_irq = gpio_fwd_to_irq;
0451     chip->base = -1;
0452     chip->ngpio = ngpios;
0453     fwd->descs = descs;
0454 
0455     if (chip->can_sleep)
0456         mutex_init(&fwd->mlock);
0457     else
0458         spin_lock_init(&fwd->slock);
0459 
0460     error = devm_gpiochip_add_data(dev, chip, fwd);
0461     if (error)
0462         return ERR_PTR(error);
0463 
0464     return fwd;
0465 }
0466 
0467 
0468 /*
0469  *  GPIO Aggregator platform device
0470  */
0471 
0472 static int gpio_aggregator_probe(struct platform_device *pdev)
0473 {
0474     struct device *dev = &pdev->dev;
0475     struct gpio_desc **descs;
0476     struct gpiochip_fwd *fwd;
0477     int i, n;
0478 
0479     n = gpiod_count(dev, NULL);
0480     if (n < 0)
0481         return n;
0482 
0483     descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL);
0484     if (!descs)
0485         return -ENOMEM;
0486 
0487     for (i = 0; i < n; i++) {
0488         descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
0489         if (IS_ERR(descs[i]))
0490             return PTR_ERR(descs[i]);
0491     }
0492 
0493     fwd = gpiochip_fwd_create(dev, n, descs);
0494     if (IS_ERR(fwd))
0495         return PTR_ERR(fwd);
0496 
0497     platform_set_drvdata(pdev, fwd);
0498     return 0;
0499 }
0500 
0501 #ifdef CONFIG_OF
0502 static const struct of_device_id gpio_aggregator_dt_ids[] = {
0503     /*
0504      * Add GPIO-operated devices controlled from userspace below,
0505      * or use "driver_override" in sysfs
0506      */
0507     {}
0508 };
0509 MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
0510 #endif
0511 
0512 static struct platform_driver gpio_aggregator_driver = {
0513     .probe = gpio_aggregator_probe,
0514     .driver = {
0515         .name = DRV_NAME,
0516         .groups = gpio_aggregator_groups,
0517         .of_match_table = of_match_ptr(gpio_aggregator_dt_ids),
0518     },
0519 };
0520 
0521 static int __init gpio_aggregator_init(void)
0522 {
0523     return platform_driver_register(&gpio_aggregator_driver);
0524 }
0525 module_init(gpio_aggregator_init);
0526 
0527 static void __exit gpio_aggregator_exit(void)
0528 {
0529     gpio_aggregator_remove_all();
0530     platform_driver_unregister(&gpio_aggregator_driver);
0531 }
0532 module_exit(gpio_aggregator_exit);
0533 
0534 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
0535 MODULE_DESCRIPTION("GPIO Aggregator");
0536 MODULE_LICENSE("GPL v2");
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