[PATCH 3/3] mtd: rawnand: qcom: Add support for secure regions in NAND memory

Manivannan Sadhasivam
2021-02-22T12:04:02Z

On a typical end product, a vendor may choose to secure some regions in
the NAND memory which are supposed to stay intact between FW upgrades.
The access to those regions will be blocked by a secure element like
Trustzone. So the normal world software like Linux kernel should not
touch these regions (including reading).

The regions are declared using a DT property, "qcom,secure-regions".
So let's make use of this property and skip access to the secure regions
present in a system.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
drivers/mtd/nand/raw/qcom_nandc.c | 72 +++++++++++++++++++++++++++----
1 file changed, 63 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
index fd4c318b520f..c2dc99c1b2f1 100644
--- a/drivers/mtd/nand/raw/qcom_nandc.c
+++ b/drivers/mtd/nand/raw/qcom_nandc.c
@@ -431,6 +431,11 @@ struct qcom_nand_controller {
* @cfg0, cfg1, cfg0_raw..: NANDc register configurations needed for
* ecc/non-ecc mode for the current nand flash
* device
+ *
+ * @sec_regions: Array representing the secure regions in the
+ * NAND chip
+ *
+ * @nr_sec_regions: Number of secure regions in the NAND chip
*/
struct qcom_nand_host {
struct nand_chip chip;
@@ -453,6 +458,9 @@ struct qcom_nand_host {
u32 ecc_bch_cfg;
u32 clrflashstatus;
u32 clrreadstatus;
+
+ u32 *sec_regions;
+ u8 nr_sec_regions;
};

/*
@@ -662,16 +670,27 @@ static void nandc_set_reg(struct qcom_nand_controller *nandc, int offset,
}

/* helper to configure address register values */
-static void set_address(struct qcom_nand_host *host, u16 column, int page)
+static int set_address(struct qcom_nand_host *host, u16 column, int page)
{
struct nand_chip *chip = &host->chip;
struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
+ u32 offs = page << chip->page_shift;
+ int i, j;
+
+ /* Skip touching the secure regions if present */
+ for (i = 0, j = 0; i < host->nr_sec_regions; i++, j += 2) {
+ if (offs >= host->sec_regions[j] &&
+ (offs <= host->sec_regions[j] + host->sec_regions[j + 1]))
+ return -EIO;
+ }

if (chip->options & NAND_BUSWIDTH_16)
column >>= 1;

nandc_set_reg(nandc, NAND_ADDR0, page << 16 | column);
nandc_set_reg(nandc, NAND_ADDR1, page >> 16 & 0xff);
+
+ return 0;
}

/*
@@ -1491,13 +1510,13 @@ static void qcom_nandc_command(struct nand_chip *chip, unsigned int command,
WARN_ON(column != 0);

host->use_ecc = true;
- set_address(host, 0, page_addr);
+ ret = set_address(host, 0, page_addr);
update_rw_regs(host, ecc->steps, true);
break;

case NAND_CMD_SEQIN:
WARN_ON(column != 0);
- set_address(host, 0, page_addr);
+ ret = set_address(host, 0, page_addr);
break;

case NAND_CMD_PAGEPROG:
@@ -1615,7 +1634,10 @@ qcom_nandc_read_cw_raw(struct mtd_info *mtd, struct nand_chip *chip,
host->use_ecc = false;

clear_bam_transaction(nandc);
- set_address(host, host->cw_size * cw, page);
+ ret = set_address(host, host->cw_size * cw, page);
+ if (ret)
+ return ret;
+
update_rw_regs(host, 1, true);
config_nand_page_read(nandc);

@@ -1943,7 +1965,10 @@ static int copy_last_cw(struct qcom_nand_host *host, int page)
/* prepare a clean read buffer */
memset(nandc->data_buffer, 0xff, size);

- set_address(host, host->cw_size * (ecc->steps - 1), page);
+ ret = set_address(host, host->cw_size * (ecc->steps - 1), page);
+ if (ret)
+ return ret;
+
update_rw_regs(host, 1, true);

config_nand_single_cw_page_read(nandc, host->use_ecc);
@@ -2005,12 +2030,16 @@ static int qcom_nandc_read_oob(struct nand_chip *chip, int page)
struct qcom_nand_host *host = to_qcom_nand_host(chip);
struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
struct nand_ecc_ctrl *ecc = &chip->ecc;
+ int ret;

clear_read_regs(nandc);
clear_bam_transaction(nandc);

host->use_ecc = true;
- set_address(host, 0, page);
+ ret = set_address(host, 0, page);
+ if (ret)
+ return ret;
+
update_rw_regs(host, ecc->steps, true);

return read_page_ecc(host, NULL, chip->oob_poi, page);
@@ -2188,7 +2217,10 @@ static int qcom_nandc_write_oob(struct nand_chip *chip, int page)
mtd_ooblayout_get_databytes(mtd, nandc->data_buffer + data_size, oob,
0, mtd->oobavail);

- set_address(host, host->cw_size * (ecc->steps - 1), page);
+ ret = set_address(host, host->cw_size * (ecc->steps - 1), page);
+ if (ret)
+ return ret;
+
update_rw_regs(host, 1, false);

config_nand_page_write(nandc);
@@ -2267,7 +2299,10 @@ static int qcom_nandc_block_markbad(struct nand_chip *chip, loff_t ofs)

/* prepare write */
host->use_ecc = false;
- set_address(host, host->cw_size * (ecc->steps - 1), page);
+ ret = set_address(host, host->cw_size * (ecc->steps - 1), page);
+ if (ret)
+ return ret;
+
update_rw_regs(host, 1, false);

config_nand_page_write(nandc);
@@ -2830,7 +2865,8 @@ static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
struct nand_chip *chip = &host->chip;
struct mtd_info *mtd = nand_to_mtd(chip);
struct device *dev = nandc->dev;
- int ret;
+ struct property *prop;
+ int ret, length, nr_elem;

ret = of_property_read_u32(dn, "reg", &host->cs);
if (ret) {
@@ -2886,6 +2922,24 @@ static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc,
}
}

+ /*
+ * Look for secure regions in the NAND chip. These regions are supposed
+ * to be protected by a secure element like Trustzone. So the read/write
+ * accesses to these regions will be blocked in the runtime by this
+ * driver.
+ */
+ prop = of_find_property(dn, "qcom,secure-regions", &length);
+ if (prop) {
+ nr_elem = length / sizeof(u32);
+ host->nr_sec_regions = nr_elem / 2;
+
+ host->sec_regions = devm_kcalloc(dev, nr_elem, sizeof(u32), GFP_KERNEL);
+ if (!host->sec_regions)
+ return -ENOMEM;
+
+ of_property_read_u32_array(dn, "qcom,secure-regions", host->sec_regions, nr_elem);
+ }
+
ret = mtd_device_parse_register(mtd, probes, NULL, NULL, 0);
if (ret)
nand_cleanup(chip);
--
2.25.1