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Linux/drivers/mtd/devices/elm.c

  1 /*
  2  * Error Location Module
  3  *
  4  * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 14  * GNU General Public License for more details.
 15  *
 16  */
 17 
 18 #define DRIVER_NAME     "omap-elm"
 19 
 20 #include <linux/platform_device.h>
 21 #include <linux/module.h>
 22 #include <linux/interrupt.h>
 23 #include <linux/io.h>
 24 #include <linux/of.h>
 25 #include <linux/sched.h>
 26 #include <linux/pm_runtime.h>
 27 #include <linux/platform_data/elm.h>
 28 
 29 #define ELM_SYSCONFIG                   0x010
 30 #define ELM_IRQSTATUS                   0x018
 31 #define ELM_IRQENABLE                   0x01c
 32 #define ELM_LOCATION_CONFIG             0x020
 33 #define ELM_PAGE_CTRL                   0x080
 34 #define ELM_SYNDROME_FRAGMENT_0         0x400
 35 #define ELM_SYNDROME_FRAGMENT_1         0x404
 36 #define ELM_SYNDROME_FRAGMENT_2         0x408
 37 #define ELM_SYNDROME_FRAGMENT_3         0x40c
 38 #define ELM_SYNDROME_FRAGMENT_4         0x410
 39 #define ELM_SYNDROME_FRAGMENT_5         0x414
 40 #define ELM_SYNDROME_FRAGMENT_6         0x418
 41 #define ELM_LOCATION_STATUS             0x800
 42 #define ELM_ERROR_LOCATION_0            0x880
 43 
 44 /* ELM Interrupt Status Register */
 45 #define INTR_STATUS_PAGE_VALID          BIT(8)
 46 
 47 /* ELM Interrupt Enable Register */
 48 #define INTR_EN_PAGE_MASK               BIT(8)
 49 
 50 /* ELM Location Configuration Register */
 51 #define ECC_BCH_LEVEL_MASK              0x3
 52 
 53 /* ELM syndrome */
 54 #define ELM_SYNDROME_VALID              BIT(16)
 55 
 56 /* ELM_LOCATION_STATUS Register */
 57 #define ECC_CORRECTABLE_MASK            BIT(8)
 58 #define ECC_NB_ERRORS_MASK              0x1f
 59 
 60 /* ELM_ERROR_LOCATION_0-15 Registers */
 61 #define ECC_ERROR_LOCATION_MASK         0x1fff
 62 
 63 #define ELM_ECC_SIZE                    0x7ff
 64 
 65 #define SYNDROME_FRAGMENT_REG_SIZE      0x40
 66 #define ERROR_LOCATION_SIZE             0x100
 67 
 68 struct elm_registers {
 69         u32 elm_irqenable;
 70         u32 elm_sysconfig;
 71         u32 elm_location_config;
 72         u32 elm_page_ctrl;
 73         u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
 74         u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
 75         u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
 76         u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
 77         u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
 78         u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
 79         u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
 80 };
 81 
 82 struct elm_info {
 83         struct device *dev;
 84         void __iomem *elm_base;
 85         struct completion elm_completion;
 86         struct list_head list;
 87         enum bch_ecc bch_type;
 88         struct elm_registers elm_regs;
 89         int ecc_steps;
 90         int ecc_syndrome_size;
 91 };
 92 
 93 static LIST_HEAD(elm_devices);
 94 
 95 static void elm_write_reg(struct elm_info *info, int offset, u32 val)
 96 {
 97         writel(val, info->elm_base + offset);
 98 }
 99 
100 static u32 elm_read_reg(struct elm_info *info, int offset)
101 {
102         return readl(info->elm_base + offset);
103 }
104 
105 /**
106  * elm_config - Configure ELM module
107  * @dev:        ELM device
108  * @bch_type:   Type of BCH ecc
109  */
110 int elm_config(struct device *dev, enum bch_ecc bch_type,
111         int ecc_steps, int ecc_step_size, int ecc_syndrome_size)
112 {
113         u32 reg_val;
114         struct elm_info *info = dev_get_drvdata(dev);
115 
116         if (!info) {
117                 dev_err(dev, "Unable to configure elm - device not probed?\n");
118                 return -ENODEV;
119         }
120         /* ELM cannot detect ECC errors for chunks > 1KB */
121         if (ecc_step_size > ((ELM_ECC_SIZE + 1) / 2)) {
122                 dev_err(dev, "unsupported config ecc-size=%d\n", ecc_step_size);
123                 return -EINVAL;
124         }
125         /* ELM support 8 error syndrome process */
126         if (ecc_steps > ERROR_VECTOR_MAX) {
127                 dev_err(dev, "unsupported config ecc-step=%d\n", ecc_steps);
128                 return -EINVAL;
129         }
130 
131         reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
132         elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
133         info->bch_type          = bch_type;
134         info->ecc_steps         = ecc_steps;
135         info->ecc_syndrome_size = ecc_syndrome_size;
136 
137         return 0;
138 }
139 EXPORT_SYMBOL(elm_config);
140 
141 /**
142  * elm_configure_page_mode - Enable/Disable page mode
143  * @info:       elm info
144  * @index:      index number of syndrome fragment vector
145  * @enable:     enable/disable flag for page mode
146  *
147  * Enable page mode for syndrome fragment index
148  */
149 static void elm_configure_page_mode(struct elm_info *info, int index,
150                 bool enable)
151 {
152         u32 reg_val;
153 
154         reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
155         if (enable)
156                 reg_val |= BIT(index);  /* enable page mode */
157         else
158                 reg_val &= ~BIT(index); /* disable page mode */
159 
160         elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
161 }
162 
163 /**
164  * elm_load_syndrome - Load ELM syndrome reg
165  * @info:       elm info
166  * @err_vec:    elm error vectors
167  * @ecc:        buffer with calculated ecc
168  *
169  * Load syndrome fragment registers with calculated ecc in reverse order.
170  */
171 static void elm_load_syndrome(struct elm_info *info,
172                 struct elm_errorvec *err_vec, u8 *ecc)
173 {
174         int i, offset;
175         u32 val;
176 
177         for (i = 0; i < info->ecc_steps; i++) {
178 
179                 /* Check error reported */
180                 if (err_vec[i].error_reported) {
181                         elm_configure_page_mode(info, i, true);
182                         offset = ELM_SYNDROME_FRAGMENT_0 +
183                                 SYNDROME_FRAGMENT_REG_SIZE * i;
184                         switch (info->bch_type) {
185                         case BCH8_ECC:
186                                 /* syndrome fragment 0 = ecc[9-12B] */
187                                 val = cpu_to_be32(*(u32 *) &ecc[9]);
188                                 elm_write_reg(info, offset, val);
189 
190                                 /* syndrome fragment 1 = ecc[5-8B] */
191                                 offset += 4;
192                                 val = cpu_to_be32(*(u32 *) &ecc[5]);
193                                 elm_write_reg(info, offset, val);
194 
195                                 /* syndrome fragment 2 = ecc[1-4B] */
196                                 offset += 4;
197                                 val = cpu_to_be32(*(u32 *) &ecc[1]);
198                                 elm_write_reg(info, offset, val);
199 
200                                 /* syndrome fragment 3 = ecc[0B] */
201                                 offset += 4;
202                                 val = ecc[0];
203                                 elm_write_reg(info, offset, val);
204                                 break;
205                         case BCH4_ECC:
206                                 /* syndrome fragment 0 = ecc[20-52b] bits */
207                                 val = (cpu_to_be32(*(u32 *) &ecc[3]) >> 4) |
208                                         ((ecc[2] & 0xf) << 28);
209                                 elm_write_reg(info, offset, val);
210 
211                                 /* syndrome fragment 1 = ecc[0-20b] bits */
212                                 offset += 4;
213                                 val = cpu_to_be32(*(u32 *) &ecc[0]) >> 12;
214                                 elm_write_reg(info, offset, val);
215                                 break;
216                         default:
217                                 pr_err("invalid config bch_type\n");
218                         }
219                 }
220 
221                 /* Update ecc pointer with ecc byte size */
222                 ecc += info->ecc_syndrome_size;
223         }
224 }
225 
226 /**
227  * elm_start_processing - start elm syndrome processing
228  * @info:       elm info
229  * @err_vec:    elm error vectors
230  *
231  * Set syndrome valid bit for syndrome fragment registers for which
232  * elm syndrome fragment registers are loaded. This enables elm module
233  * to start processing syndrome vectors.
234  */
235 static void elm_start_processing(struct elm_info *info,
236                 struct elm_errorvec *err_vec)
237 {
238         int i, offset;
239         u32 reg_val;
240 
241         /*
242          * Set syndrome vector valid, so that ELM module
243          * will process it for vectors error is reported
244          */
245         for (i = 0; i < info->ecc_steps; i++) {
246                 if (err_vec[i].error_reported) {
247                         offset = ELM_SYNDROME_FRAGMENT_6 +
248                                 SYNDROME_FRAGMENT_REG_SIZE * i;
249                         reg_val = elm_read_reg(info, offset);
250                         reg_val |= ELM_SYNDROME_VALID;
251                         elm_write_reg(info, offset, reg_val);
252                 }
253         }
254 }
255 
256 /**
257  * elm_error_correction - locate correctable error position
258  * @info:       elm info
259  * @err_vec:    elm error vectors
260  *
261  * On completion of processing by elm module, error location status
262  * register updated with correctable/uncorrectable error information.
263  * In case of correctable errors, number of errors located from
264  * elm location status register & read the positions from
265  * elm error location register.
266  */
267 static void elm_error_correction(struct elm_info *info,
268                 struct elm_errorvec *err_vec)
269 {
270         int i, j, errors = 0;
271         int offset;
272         u32 reg_val;
273 
274         for (i = 0; i < info->ecc_steps; i++) {
275 
276                 /* Check error reported */
277                 if (err_vec[i].error_reported) {
278                         offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
279                         reg_val = elm_read_reg(info, offset);
280 
281                         /* Check correctable error or not */
282                         if (reg_val & ECC_CORRECTABLE_MASK) {
283                                 offset = ELM_ERROR_LOCATION_0 +
284                                         ERROR_LOCATION_SIZE * i;
285 
286                                 /* Read count of correctable errors */
287                                 err_vec[i].error_count = reg_val &
288                                         ECC_NB_ERRORS_MASK;
289 
290                                 /* Update the error locations in error vector */
291                                 for (j = 0; j < err_vec[i].error_count; j++) {
292 
293                                         reg_val = elm_read_reg(info, offset);
294                                         err_vec[i].error_loc[j] = reg_val &
295                                                 ECC_ERROR_LOCATION_MASK;
296 
297                                         /* Update error location register */
298                                         offset += 4;
299                                 }
300 
301                                 errors += err_vec[i].error_count;
302                         } else {
303                                 err_vec[i].error_uncorrectable = true;
304                         }
305 
306                         /* Clearing interrupts for processed error vectors */
307                         elm_write_reg(info, ELM_IRQSTATUS, BIT(i));
308 
309                         /* Disable page mode */
310                         elm_configure_page_mode(info, i, false);
311                 }
312         }
313 }
314 
315 /**
316  * elm_decode_bch_error_page - Locate error position
317  * @dev:        device pointer
318  * @ecc_calc:   calculated ECC bytes from GPMC
319  * @err_vec:    elm error vectors
320  *
321  * Called with one or more error reported vectors & vectors with
322  * error reported is updated in err_vec[].error_reported
323  */
324 void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
325                 struct elm_errorvec *err_vec)
326 {
327         struct elm_info *info = dev_get_drvdata(dev);
328         u32 reg_val;
329 
330         /* Enable page mode interrupt */
331         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
332         elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
333         elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);
334 
335         /* Load valid ecc byte to syndrome fragment register */
336         elm_load_syndrome(info, err_vec, ecc_calc);
337 
338         /* Enable syndrome processing for which syndrome fragment is updated */
339         elm_start_processing(info, err_vec);
340 
341         /* Wait for ELM module to finish locating error correction */
342         wait_for_completion(&info->elm_completion);
343 
344         /* Disable page mode interrupt */
345         reg_val = elm_read_reg(info, ELM_IRQENABLE);
346         elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
347         elm_error_correction(info, err_vec);
348 }
349 EXPORT_SYMBOL(elm_decode_bch_error_page);
350 
351 static irqreturn_t elm_isr(int this_irq, void *dev_id)
352 {
353         u32 reg_val;
354         struct elm_info *info = dev_id;
355 
356         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
357 
358         /* All error vectors processed */
359         if (reg_val & INTR_STATUS_PAGE_VALID) {
360                 elm_write_reg(info, ELM_IRQSTATUS,
361                                 reg_val & INTR_STATUS_PAGE_VALID);
362                 complete(&info->elm_completion);
363                 return IRQ_HANDLED;
364         }
365 
366         return IRQ_NONE;
367 }
368 
369 static int elm_probe(struct platform_device *pdev)
370 {
371         int ret = 0;
372         struct resource *res, *irq;
373         struct elm_info *info;
374 
375         info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
376         if (!info)
377                 return -ENOMEM;
378 
379         info->dev = &pdev->dev;
380 
381         irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
382         if (!irq) {
383                 dev_err(&pdev->dev, "no irq resource defined\n");
384                 return -ENODEV;
385         }
386 
387         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
388         info->elm_base = devm_ioremap_resource(&pdev->dev, res);
389         if (IS_ERR(info->elm_base))
390                 return PTR_ERR(info->elm_base);
391 
392         ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
393                         pdev->name, info);
394         if (ret) {
395                 dev_err(&pdev->dev, "failure requesting irq %i\n", irq->start);
396                 return ret;
397         }
398 
399         pm_runtime_enable(&pdev->dev);
400         if (pm_runtime_get_sync(&pdev->dev) < 0) {
401                 ret = -EINVAL;
402                 pm_runtime_disable(&pdev->dev);
403                 dev_err(&pdev->dev, "can't enable clock\n");
404                 return ret;
405         }
406 
407         init_completion(&info->elm_completion);
408         INIT_LIST_HEAD(&info->list);
409         list_add(&info->list, &elm_devices);
410         platform_set_drvdata(pdev, info);
411         return ret;
412 }
413 
414 static int elm_remove(struct platform_device *pdev)
415 {
416         pm_runtime_put_sync(&pdev->dev);
417         pm_runtime_disable(&pdev->dev);
418         return 0;
419 }
420 
421 /**
422  * elm_context_save
423  * saves ELM configurations to preserve them across Hardware powered-down
424  */
425 static int elm_context_save(struct elm_info *info)
426 {
427         struct elm_registers *regs = &info->elm_regs;
428         enum bch_ecc bch_type = info->bch_type;
429         u32 offset = 0, i;
430 
431         regs->elm_irqenable       = elm_read_reg(info, ELM_IRQENABLE);
432         regs->elm_sysconfig       = elm_read_reg(info, ELM_SYSCONFIG);
433         regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
434         regs->elm_page_ctrl       = elm_read_reg(info, ELM_PAGE_CTRL);
435         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
436                 offset = i * SYNDROME_FRAGMENT_REG_SIZE;
437                 switch (bch_type) {
438                 case BCH8_ECC:
439                         regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
440                                         ELM_SYNDROME_FRAGMENT_3 + offset);
441                         regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
442                                         ELM_SYNDROME_FRAGMENT_2 + offset);
443                 case BCH4_ECC:
444                         regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
445                                         ELM_SYNDROME_FRAGMENT_1 + offset);
446                         regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
447                                         ELM_SYNDROME_FRAGMENT_0 + offset);
448                 default:
449                         return -EINVAL;
450                 }
451                 /* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
452                  * to be saved for all BCH schemes*/
453                 regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
454                                         ELM_SYNDROME_FRAGMENT_6 + offset);
455         }
456         return 0;
457 }
458 
459 /**
460  * elm_context_restore
461  * writes configurations saved duing power-down back into ELM registers
462  */
463 static int elm_context_restore(struct elm_info *info)
464 {
465         struct elm_registers *regs = &info->elm_regs;
466         enum bch_ecc bch_type = info->bch_type;
467         u32 offset = 0, i;
468 
469         elm_write_reg(info, ELM_IRQENABLE,       regs->elm_irqenable);
470         elm_write_reg(info, ELM_SYSCONFIG,       regs->elm_sysconfig);
471         elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
472         elm_write_reg(info, ELM_PAGE_CTRL,       regs->elm_page_ctrl);
473         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
474                 offset = i * SYNDROME_FRAGMENT_REG_SIZE;
475                 switch (bch_type) {
476                 case BCH8_ECC:
477                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
478                                         regs->elm_syndrome_fragment_3[i]);
479                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
480                                         regs->elm_syndrome_fragment_2[i]);
481                 case BCH4_ECC:
482                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
483                                         regs->elm_syndrome_fragment_1[i]);
484                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
485                                         regs->elm_syndrome_fragment_0[i]);
486                 default:
487                         return -EINVAL;
488                 }
489                 /* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
490                 elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
491                                         regs->elm_syndrome_fragment_6[i] &
492                                                          ELM_SYNDROME_VALID);
493         }
494         return 0;
495 }
496 
497 static int elm_suspend(struct device *dev)
498 {
499         struct elm_info *info = dev_get_drvdata(dev);
500         elm_context_save(info);
501         pm_runtime_put_sync(dev);
502         return 0;
503 }
504 
505 static int elm_resume(struct device *dev)
506 {
507         struct elm_info *info = dev_get_drvdata(dev);
508         pm_runtime_get_sync(dev);
509         elm_context_restore(info);
510         return 0;
511 }
512 
513 static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);
514 
515 #ifdef CONFIG_OF
516 static const struct of_device_id elm_of_match[] = {
517         { .compatible = "ti,am3352-elm" },
518         {},
519 };
520 MODULE_DEVICE_TABLE(of, elm_of_match);
521 #endif
522 
523 static struct platform_driver elm_driver = {
524         .driver = {
525                 .name   = DRIVER_NAME,
526                 .owner  = THIS_MODULE,
527                 .of_match_table = of_match_ptr(elm_of_match),
528                 .pm     = &elm_pm_ops,
529         },
530         .probe  = elm_probe,
531         .remove = elm_remove,
532 };
533 
534 module_platform_driver(elm_driver);
535 
536 MODULE_DESCRIPTION("ELM driver for BCH error correction");
537 MODULE_AUTHOR("Texas Instruments");
538 MODULE_ALIAS("platform: elm");
539 MODULE_LICENSE("GPL v2");
540 

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