[PATCH 3/3] mtd: add SMEM parser for QCOM platforms
Mathieu Olivari
mathieu at codeaurora.org
Mon Aug 17 14:24:52 PDT 2015
On Fri, Aug 14, 2015 at 10:48:17PM -0700, Bjorn Andersson wrote:
> On Fri 14 Aug 17:46 PDT 2015, Mathieu Olivari wrote:
>
> > On QCOM platforms using MTD devices storage (such as IPQ806x), SMEM is
> > used to store partition layout. This new parser can now be used to read
> > SMEM and use it to register an MTD layout according to its content.
> >
>
> Nice to see another user of the smem code :)
>
> > diff --git a/drivers/mtd/qcom_smem_part.c b/drivers/mtd/qcom_smem_part.c
> [..]
> > +
> > +/* Processor/host identifier for the application processor */
> > +#define SMEM_HOST_APPS 0
>
> This makes me wonder if there will ever be an apps partition. I would
> have picked QCOM_SMEM_HOST_ANY, but I don't know what future platforms
> might hold for us.
>
>
> And as a side note, I think I will propose that we rename that define
> QCOM_SMEM_GLOBAL.
OK; I'll rename it in QCOM_SMEM_GLOBAL then to be in sync.
>
> > +
> > +/* SMEM items index */
> > +#define SMEM_AARM_PARTITION_TABLE 9
> > +#define SMEM_BOOT_FLASH_TYPE 421
> > +#define SMEM_BOOT_FLASH_BLOCK_SIZE 424
> > +
> > +/* SMEM Flash types */
> > +#define SMEM_FLASH_NAND 2
> > +#define SMEM_FLASH_SPI 6
> > +
> > +#define SMEM_PART_NAME_SZ 16
> > +#define SMEM_PARTS_MAX 32
> > +
> > +struct smem_partition {
> > + char name[SMEM_PART_NAME_SZ];
> > + __le32 start;
> > + __le32 size;
> > + __le32 attr;
> > +};
> > +
> > +struct smem_partition_table {
> > + u8 magic[8];
> > + __le32 version;
> > + __le32 len;
> > + struct smem_partition parts[SMEM_PARTS_MAX];
> > +};
> > +
> > +/* SMEM Magic values in partition table */
> > +static const u8 SMEM_PTABLE_MAGIC[] = {
> > + 0xaa, 0x73, 0xee, 0x55,
> > + 0xdb, 0xbd, 0x5e, 0xe3,
> > +};
> > +
> > +static int qcom_smem_get_flash_blksz(u64 **smem_blksz)
>
> Instead of passing pointers around I think you should just make this
> function return < 0 for errors and >= 0 for the requested data. You can
> probably still have it as an int, as the current values are well below
> the size of the int.
Good point. Thanks. I'll report it.
>
> > +{
> > + int ret;
> > + size_t size;
> > +
> > + ret = qcom_smem_get(SMEM_HOST_APPS, SMEM_BOOT_FLASH_BLOCK_SIZE,
> > + (void **) smem_blksz, &size);
> > +
> > + if (ret < 0) {
> > + pr_err("Unable to read flash blksz from SMEM\n");
> > + return -ENOENT;
> > + }
> > +
> > + if (size != sizeof(**smem_blksz)) {
> > + pr_err("Invalid flash blksz size in SMEM\n");
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int qcom_smem_get_flash_type(u64 **smem_flash_type)
>
> Same as above.
OK.
>
> > +{
> > + int ret;
> > + size_t size;
> > +
> > + ret = qcom_smem_get(SMEM_HOST_APPS, SMEM_BOOT_FLASH_TYPE,
> > + (void **) smem_flash_type, &size);
> > +
> > + if (ret < 0) {
> > + pr_err("Unable to read flash type from SMEM\n");
> > + return -ENOENT;
> > + }
> > +
> > + if (size != sizeof(**smem_flash_type)) {
> > + pr_err("Invalid flash type size in SMEM\n");
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int qcom_smem_get_flash_partitions(struct smem_partition_table **pparts)
> > +{
> > + int ret;
> > + size_t size;
> > +
> > + ret = qcom_smem_get(SMEM_HOST_APPS, SMEM_AARM_PARTITION_TABLE,
> > + (void **) pparts, &size);
> > +
>
> If you don't care about the size just pass NULL as the last argument.
OK.
>
> > + if (ret < 0) {
> > + pr_err("Unable to read partition table from SMEM\n");
> > + return -ENOENT;
> > + }
>
> I think it would be cleaner if you had this function check the magic and
> version and then return the partition pointer. That is:
>
> static smem_partition *qcom_smem_get_flash_partitions(size_t *count)
>
>
> And make *count = le32_to_cpu(table->len); so you don't have to care
> about that below.
>
> (And use NULL or ERR_PTR for the error paths)
Same; good idea. I'll make the mod.
>
> > +
> > + return 0;
> > +}
> > +
> > +static int of_dev_node_match(struct device *dev, void *data)
> > +{
> > + return dev->of_node == data;
> > +}
> > +
> > +static bool is_spi_device(struct device_node *np)
> > +{
> > + struct device *dev;
> > +
> > + dev = bus_find_device(&spi_bus_type, NULL, np, of_dev_node_match);
> > + if (!dev)
> > + return false;
> > +
> > + put_device(dev);
> > + return true;
> > +}
> > +
> > +static int parse_qcom_smem_partitions(struct mtd_info *master,
> > + struct mtd_partition **pparts,
> > + struct mtd_part_parser_data *data)
> > +{
> > + struct smem_partition_table *smem_parts;
> > + u64 *smem_flash_type, *smem_blksz;
> > + struct mtd_partition *mtd_parts;
> > + struct device_node *of_node = data->of_node;
> > + int i, ret;
> > +
> > + /*
> > + * SMEM will only store the partition table of the boot device.
> > + * If this is not the boot device, do not return any partition.
> > + */
>
> I guess this is the result of below checks, but it's not describing
> what's actually done here. I think it should say "only parse
> partitions on the specified memory type" or something like that.
OK.
>
> > + ret = qcom_smem_get_flash_type(&smem_flash_type);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if ((*smem_flash_type == SMEM_FLASH_NAND && !mtd_type_is_nand(master))
> > + || (*smem_flash_type == SMEM_FLASH_SPI && !is_spi_device(of_node)))
> > + return 0;
> > +
> > + /*
> > + * Just for sanity purpose, make sure the block size in SMEM matches the
> > + * block size of the MTD device
> > + */
>
> Well, this is not only for sanity purpose, as you multiply all sizes
> with this number below...
I'll update the comment.
>
> > + ret = qcom_smem_get_flash_blksz(&smem_blksz);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if (*smem_blksz != master->erasesize) {
> > + pr_err("SMEM block size differs from MTD block size\n");
> > + return -EINVAL;
> > + }
> > +
> > + /* Get partition pointer from SMEM */
> > + ret = qcom_smem_get_flash_partitions(&smem_parts);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if (memcmp(SMEM_PTABLE_MAGIC, smem_parts->magic,
> > + sizeof(SMEM_PTABLE_MAGIC))) {
> > + pr_err("SMEM partition magic invalid\n");
> > + return -EINVAL;
> > + }
> > +
> > + /* Allocate and populate the mtd structures */
> > + mtd_parts = kcalloc(le32_to_cpu(smem_parts->len), sizeof(*mtd_parts),
> > + GFP_KERNEL);
> > + if (!mtd_parts)
> > + return -ENOMEM;
> > +
> > + for (i = 0; i < smem_parts->len; i++) {
>
> This might have the wrong endian...
Right. I'll do a le32_to_cpu()
>
> > + struct smem_partition *s_part = &smem_parts->parts[i];
> > + struct mtd_partition *m_part = &mtd_parts[i];
>
> I think Stephens suggestion was that you assign *pparts before looping
> and then you simply do:
>
> *pparts = mtd_parts;
>
> while (len--) {
> ..
>
> s_part++;
> mtd_parts++;
> }
>
> > +
> > + m_part->name = s_part->name;
>
> I tried to follow the mtd code, and I believe that this pointer might
> be freed in free_partition(). If so you must kstrdup it here.
OK.
>
> > + m_part->size = le32_to_cpu(s_part->size) * (*smem_blksz);
> > + m_part->offset = le32_to_cpu(s_part->start) * (*smem_blksz);
> > +
> > + /*
> > + * The last SMEM partition may have its size marked as
> > + * something like 0xffffffff, which means "until the end of the
> > + * flash device". In this case, truncate it.
> > + */
> > + if (m_part->offset + m_part->size > master->size)
> > + m_part->size = master->size - m_part->offset;
> > + }
> > +
> > + *pparts = mtd_parts;
> > +
> > + return smem_parts->len;
>
> Again, this might be in the wrong endian.
Yes.
>
> > +}
> > +
> > +static struct mtd_part_parser qcom_smem_parser = {
> > + .owner = THIS_MODULE,
> > + .parse_fn = parse_qcom_smem_partitions,
> > + .name = "qcom-smem",
> > +};
> > +
> > +static int __init qcom_smem_parser_init(void)
> > +{
> > + register_mtd_parser(&qcom_smem_parser);
> > + return 0;
> > +}
> > +
> > +static void __exit qcom_smem_parser_exit(void)
> > +{
> > + deregister_mtd_parser(&qcom_smem_parser);
> > +}
> > +
> > +module_init(qcom_smem_parser_init);
> > +module_exit(qcom_smem_parser_exit);
>
> Mostly unrelated to this patch; This makes me appreciate the
> module_platform_driver() macro, would be nice to see a patch that
> introduces something similar for partition parsers.
>
> > +
> > +MODULE_LICENSE("GPL");
>
> Are you sure you don't mean "GPL v2" here?
I'll update it.
>
> > +MODULE_AUTHOR("Mathieu Olivari <mathieu at codeaurora.org>");
> > +MODULE_DESCRIPTION("Parsing code for SMEM based partition tables");
>
> Regards,
> Bjorn
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