[PATCH v2 3/3] mtd: rawnand: qcom: Add support for secure regions in NAND memory

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

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 NAND chip DT property,
"nand-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..aa4ca298d357 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, "nand-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, "nand-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