[PATCH V2] drivers/mtd: add powernv flash MTD abstraction driver
Cedric Le Goater
clg at fr.ibm.com
Fri May 29 17:27:58 AEST 2015
Hello,
On 05/28/2015 07:25 PM, Neelesh Gupta wrote:
>
>
> On 05/28/2015 06:36 PM, Cyril Bur wrote:
>> Powerpc powernv platforms allow access to certain system flash devices
>> through a firmwarwe interface. This change adds an mtd driver for these
>> flash devices.
>>
>> Minor updates from Jeremy Kerr and Joel Stanley.
>>
>> Signed-off-by: Cyril Bur <cyrilbur at gmail.com>
>> Signed-off-by: Joel Stanley <joel at jms.id.au>
>> Signed-off-by: Jeremy Kerr <jk at ozlabs.org>
>> ---
>> V2: Address Brian Norris' review
>> Fix typos
>> Change from NAND flash type to NOR flash type
>> Correctness tweaks
>> ---
>> drivers/mtd/devices/Kconfig | 8 +
>> drivers/mtd/devices/Makefile | 1 +
>> drivers/mtd/devices/powernv_flash.c | 286 ++++++++++++++++++++++++++++++++++++
>> 3 files changed, 295 insertions(+)
>> create mode 100644 drivers/mtd/devices/powernv_flash.c
>>
>> diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
>> index c49d0b1..a8cc237 100644
>> --- a/drivers/mtd/devices/Kconfig
>> +++ b/drivers/mtd/devices/Kconfig
>> @@ -195,6 +195,14 @@ config MTD_BLOCK2MTD
>> Testing MTD users (eg JFFS2) on large media and media that might
>> be removed during a write (using the floppy drive).
>>
>> +config MTD_POWERNV_FLASH
>> + tristate "powernv flash MTD driver"
>> + depends on PPC_POWERNV
>> + help
>> + This provides an MTD device to access NVRAM on powernv OPAL
>
> NVRAM ? or to access FLASH device ?
>
>> + platforms from Linux. This device abstracts away the
>> + firmware interface for NVRAM access.
>> +
>> comment "Disk-On-Chip Device Drivers"
>>
>> config MTD_DOCG3
>> diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
>> index f0b0e61..7912d3a 100644
>> --- a/drivers/mtd/devices/Makefile
>> +++ b/drivers/mtd/devices/Makefile
>> @@ -16,6 +16,7 @@ obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
>> obj-$(CONFIG_MTD_SST25L) += sst25l.o
>> obj-$(CONFIG_MTD_BCM47XXSFLASH) += bcm47xxsflash.o
>> obj-$(CONFIG_MTD_ST_SPI_FSM) += st_spi_fsm.o
>> +obj-$(CONFIG_MTD_POWERNV_FLASH) += powernv_flash.o
>>
>>
>> CFLAGS_docg3.o += -I$(src)
>> diff --git a/drivers/mtd/devices/powernv_flash.c b/drivers/mtd/devices/powernv_flash.c
>> new file mode 100644
>> index 0000000..f619e4a
>> --- /dev/null
>> +++ b/drivers/mtd/devices/powernv_flash.c
>> @@ -0,0 +1,286 @@
>> +/*
>> + * OPAL PNOR flash MTD abstraction
>> + *
>> + * IBM 2015
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/errno.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/string.h>
>> +#include <linux/slab.h>
>> +#include <linux/mtd/mtd.h>
>> +#include <linux/mtd/partitions.h>
>> +
>> +#include <linux/debugfs.h>
>> +#include <linux/seq_file.h>
>> +
>> +#include <asm/opal.h>
>> +
>> +
>> +/*
>> + * This driver creates the a Linux MTD abstraction for platform PNOR flash
>> + * backed by OPAL calls
>> + */
>> +
>> +struct powernv_flash {
>> + struct mtd_info mtd;
>> + uint64_t id;
>
> 'id' should be u32
>
>> +};
>> +
>> +enum flash_op {
>> + FLASH_OP_READ,
>> + FLASH_OP_WRITE,
>> + FLASH_OP_ERASE,
>> +};
>> +
>> +static int powernv_flash_async_op(struct mtd_info *mtd, enum flash_op op,
>> + loff_t offset, size_t len, size_t *retlen, u_char *buf)
>> +{
>> + struct powernv_flash *info = (struct powernv_flash *)mtd->priv;
>> + struct device *dev = &mtd->dev;
>> + int token;
>> + struct opal_msg msg;
>> + int rc;
>> +
>> + dev_dbg(dev, "%s(op=%d, offset=0x%llx, len=%zu)\n",
>> + __func__, op, offset, len);
>> +
>> + token = opal_async_get_token_interruptible();
>> + if (token < 0) {
>> + dev_err(dev, "Failed to get an async token\n");
>> + return -ENOMEM;
>
> ENOMEM is not correct code here.. 'token' itself has the right one in case of
> failure. To be more precise,
> if (token < 0) {
> if (token != -ERESTARTSYS)
> dev_err(dev, "Failed to get an async token\n");
>
> return token;
> }
>
>> + }
>> +
>> + switch (op) {
>> + case FLASH_OP_READ:
>> + rc = opal_flash_read(info->id, offset, __pa(buf), len, token);
>> + break;
>> + case FLASH_OP_WRITE:
>> + rc = opal_flash_write(info->id, offset, __pa(buf), len, token);
>> + break;
>> + case FLASH_OP_ERASE:
>> + rc = opal_flash_erase(info->id, offset, len, token);
>> + break;
>> + default:
>> + BUG_ON(1);
>> + }
>> +
>> + if (rc != OPAL_ASYNC_COMPLETION) {
>> + dev_err(dev, "opal_flash_async_op(op=%d) failed (rc %d)\n",
>> + op, rc);
>
> release the token, opal_async_release_token();
>
>> + return -EIO;
>> + }
>> +
>> + rc = opal_async_wait_response(token, &msg);
>> + opal_async_release_token(token);
>> + if (rc) {
>> + dev_err(dev, "opal async wait failed (rc %d)\n", rc);
>> + return -EIO;
>> + }
>> +
>> + rc = be64_to_cpu(msg.params[1]);
>> + if (rc == OPAL_SUCCESS) {
>> + rc = 0;
>> + if (retlen)
>> + *retlen = len;
>> + } else {
>> + rc = -EIO;
>> + }
>> +
>
>
> return rc;
You could use opal_error_code() to convert opal codes in errnos.
Also, powernv_flash_async_op() only contains low level OPAL cookery. I think
the code would be better placed under 'arch/powerpc/platforms/powernv/' ?
Cheers,
C.
>> + return 0;
>> +}
>> +
>> +/**
>> + * @mtd: the device
>> + * @from: the offset to read from
>> + * @len: the number of bytes to read
>> + * @retlen: the number of bytes actually read
>> + * @buf: the filled in buffer
>> + *
>> + * Returns 0 if read successful, or -ERRNO if an error occurred
>> + */
>> +static int powernv_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
>> + size_t *retlen, u_char *buf)
>> +{
>> + return powernv_flash_async_op(mtd, FLASH_OP_READ, from,
>> + len, retlen, buf);
>> +}
>> +
>> +/**
>> + * @mtd: the device
>> + * @to: the offset to write to
>> + * @len: the number of bytes to write
>> + * @retlen: the number of bytes actually written
>> + * @buf: the buffer to get bytes from
>> + *
>> + * Returns 0 if write successful, -ERRNO if error occurred
>> + */
>> +static int powernv_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
>> + size_t *retlen, const u_char *buf)
>> +{
>> + return powernv_flash_async_op(mtd, FLASH_OP_WRITE, to,
>> + len, retlen, (u_char *)buf);
>
> Why typecast ? 'buf' should be 'const' for write operation.
>
>> +}
>> +
>> +/**
>> + * @mtd: the device
>> + * @erase: the erase info
>> + * Returns 0 if erase successful or -ERRNO if an error occurred
>> + */
>> +static int powernv_flash_erase(struct mtd_info *mtd, struct erase_info *erase)
>> +{
>> + int rc;
>> +
>> + erase->state = MTD_ERASING;
>> +
>> + /* todo: register our own notifier to do a true async implementation */
>> + rc = powernv_flash_async_op(mtd, FLASH_OP_ERASE, erase->addr,
>> + erase->len, NULL, NULL);
>> +
>> + if (rc) {
>> + erase->fail_addr = erase->addr;
>> + erase->state = MTD_ERASE_FAILED;
>> + } else {
>> + erase->state = MTD_ERASE_DONE;
>> + }
>> + mtd_erase_callback(erase);
>
> return rc;
>
>> + return 0;
>> +}
>> +
>> +/**
>> + * powernv_flash_set_driver_info - Fill the mtd_info structure and docg3
>> + * structure @pdev: The platform device
>> + * @mtd: The structure to fill
>> + */
>> +static int __init powernv_flash_set_driver_info(struct device *dev,
>> + struct mtd_info *mtd)
>
> Why __init tag ? Called from the probe so should not be .. ?
>
>> +{
>> + u64 size;
>> + u32 erase_size;
>> + int rc;
>> +
>> + rc = of_property_read_u32(dev->of_node, "ibm,flash-block-size",
>> + &erase_size);
>> + if (rc) {
>> + dev_err(dev, "couldn't get resource block size information\n");
>> + return rc;
>> + }
>> +
>> + rc = of_property_read_u64(dev->of_node, "reg", &size);
>> + if (rc) {
>> + dev_err(dev, "couldn't get resource size information\n");
>> + return rc;
>> + }
>> +
>> + /*
>> + * Going to have to check what details I need to set and how to
>> + * get them
>> + */
>> + mtd->name = of_get_property(dev->of_node, "name", NULL);
>> + /*
>> + * Using MTD_ABSENT as this is really just a passthrough to a firmware
>
> But you are using MTD_NORFLASH :)
>
>> + * interface
>> + */
>> + mtd->type = MTD_NORFLASH;
>> + mtd->flags = MTD_WRITEABLE;
>> + mtd->size = size;
>> + mtd->erasesize = erase_size;
>> + mtd->writebufsize = mtd->writesize = 1;
>> + mtd->owner = THIS_MODULE;
>> + mtd->_erase = powernv_flash_erase;
>> + mtd->_read = powernv_flash_read;
>> + mtd->_write = powernv_flash_write;
>> + mtd->dev.parent = dev;
>> + return 0;
>> +}
>> +
>> +/**
>> + * powernv_flash_probe
>> + * @pdev: platform device
>> + *
>> + * Returns 0 on success, -ENOMEM, -ENXIO on error
>> + */
>> +static int powernv_flash_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct powernv_flash *data;
>> + int ret;
>> +
>> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> + if (!data) {
>> + ret = -ENOMEM;
>> + goto out;
>> + }
>> + data->mtd.priv = data;
>> +
>> + ret = of_property_read_u32(dev->of_node, "ibm,opal-id", &(data->id));
>> + if (ret) {
>> + dev_err(dev, "no device property 'ibm,opal-id'\n");
>> + goto out;
>> + }
>> +
>> + ret = powernv_flash_set_driver_info(dev, &data->mtd);
>> + if (ret)
>> + goto out;
>> +
>> + /*
>> + * Skiboot does expose the partitioning information via OF and the
>> + * ofpart parser could partition it all nicely.
>> + *
>> + * The current flash that skiboot exposes is one contiguous flash chip
>> + * with an ffs partition at the start, it should prove easier for users
>> + * to deal with partitions or not as they see fit
>> + */
>> + ret = mtd_device_register(&data->mtd, NULL, 0);
>> +
>> +out:
>> + return ret;
>> +}
>> +
>> +/**
>> + * op_release - Release the driver
>> + * @pdev: the platform device
>> + *
>> + * Returns 0
>> + */
>> +static int powernv_flash_release(struct platform_device *pdev)
>> +{
>> + /* All resources should be freed automatically */
>
> Other resources are ok, but mtd device should be explicitly deleted ..
>
> Neelesh.
>
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id powernv_flash_match[] = {
>> + { .compatible = "ibm,opal-flash" },
>> + {}
>> +};
>> +
>> +static struct platform_driver powernv_flash_driver = {
>> + .driver = {
>> + .name = "powernv_flash",
>> + .of_match_table = powernv_flash_match,
>> + },
>> + .remove = powernv_flash_release,
>> + .probe = powernv_flash_probe,
>> +};
>> +
>> +module_platform_driver(powernv_flash_driver);
>> +
>> +MODULE_DEVICE_TABLE(of, powernv_flash_match);
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Cyril Bur <cyril.bur at au1.ibm.com>");
>> +MODULE_DESCRIPTION("MTD abstraction for OPAL flash");
>
>
>
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