[RFC] bcma: add support for on-chip OTP memory used for SPROM storage

["Arend van Spriel" <arend@broadcom.com>]

Wireless Broadcom chips can have either their SPROM data stored
on either external SPROM or on-chip OTP memory. Both are accessed
through the same register space. This patch adds support for the
on-chip OTP memory.

Tested with:
BCM43224 OTP and SPROM
BCM4331 SPROM
BCM4313 OTP

This patch is in response so gmane article [1].

[1] http://article.gmane.org/gmane.linux.kernel.wireless.general/85426

Cc: Saul St. John <saul.stjohn@gmail.com>
Cc: Rafal Milecki <zajec5@gmail.com>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
---
Determining the offset for OTP sprom data turned out to be
easier as it boils down to reading a register. This change
collides with patch posted by Hauke:

bcma: add support for sprom not found on the device.

Now working on changes in brcmsmac to start using the sprom
data stored in struct bcma_bus. Feel free to comment this patch.

Gr. AvS
---
 drivers/bcma/sprom.c                        |  118 ++++++++++++++++++++++++---
 include/linux/bcma/bcma_driver_chipcommon.h |    9 ++
 2 files changed, 115 insertions(+), 12 deletions(-)

diff --git a/drivers/bcma/sprom.c b/drivers/bcma/sprom.c
index ca77525..4dd537c 100644
--- a/drivers/bcma/sprom.c
+++ b/drivers/bcma/sprom.c
@@ -246,22 +246,121 @@ static void bcma_sprom_extract_r8(struct bcma_bus *bus, const u16 *sprom)
 	     SSB_SROM8_FEM_ANTSWLUT_SHIFT);
 }
 
+/*
+ * Indicates the presence of external SPROM.
+ */
+static bool bcma_sprom_ext_available(struct bcma_bus *bus)
+{
+	u32 chip_status;
+	u32 srom_control;
+	u32 present_mask;
+
+	if (bus->drv_cc.core->id.rev >= 31) {
+		if (!(bus->drv_cc.capabilities & BCMA_CC_CAP_SPROM))
+				return false;
+
+		srom_control = bcma_read32(bus->drv_cc.core,
+					   BCMA_CC_SROM_CONTROL);
+		return !!(srom_control & BCMA_CC_SROM_CONTROL_PRESENT);
+	}
+
+	/* older chipcommon revisions use chip status register */
+	chip_status = bcma_read32(bus->drv_cc.core, BCMA_CC_CHIPSTAT);
+	switch (bus->chipinfo.id) {
+	case 0x4313:
+		present_mask = BCMA_CC_CHIPST_4313_SPROM_PRESENT;
+		break;
+
+	case 0x4331:
+		present_mask = BCMA_CC_CHIPST_4331_SPROM_PRESENT;
+		break;
+
+	default:
+		return true;
+	}
+
+	return (chip_status & present_mask) == present_mask;
+}
+
+/*
+ * Indicates that on-chip OTP memory is present and enabled.
+ */
+static bool bcma_sprom_onchip_available(struct bcma_bus *bus)
+{
+	u32 chip_status;
+	u32 otpsize = 0;
+	bool present;
+
+	chip_status = bcma_read32(bus->drv_cc.core, BCMA_CC_CHIPSTAT);
+	switch (bus->chipinfo.id) {
+	case 0x4313:
+		present = chip_status & BCMA_CC_CHIPST_4313_OTP_PRESENT;
+		break;
+
+	case 0x4331:
+		present = chip_status & BCMA_CC_CHIPST_4331_OTP_PRESENT;
+		break;
+
+	case 43224:
+	case 43225:
+		/* for these chips OTP is always available */
+		present = true;
+		break;
+
+	default:
+		present = false;
+		break;
+	}
+
+	if (present) {
+		otpsize = bus->drv_cc.capabilities & BCMA_CC_CAP_OTPS;
+		otpsize >>= BCMA_CC_CAP_OTPS_SHIFT;
+	}
+
+	return otpsize != 0;
+}
+
+/*
+ * Verify OTP is filled and determine the byte
+ * offset where SPROM data is located.
+ *
+ * On error, returns 0; byte offset otherwise.
+ */
+static int bcma_sprom_onchip_offset(struct bcma_bus *bus)
+{
+	struct bcma_device *cc = bus->drv_cc.core;
+	u32 offset;
+
+	/* verify OTP status */
+	if ((bcma_read32(cc, BCMA_CC_OTPS) & BCMA_CC_OTPS_GU_PROG_HW) == 0)
+		return 0;
+
+	/* obtain bit offset from otplayout register */
+	offset = (bcma_read32(cc, BCMA_CC_OTPL) & BCMA_CC_OTPL_GURGN_OFFSET);
+	return BCMA_CC_SPROM + (offset >> 3);
+}
+
 int bcma_sprom_get(struct bcma_bus *bus)
 {
-	u16 offset;
+	u16 offset = BCMA_CC_SPROM;
 	u16 *sprom;
-	u32 sromctrl;
 	int err = 0;
 
 	if (!bus->drv_cc.core)
 		return -EOPNOTSUPP;
 
-	if (!(bus->drv_cc.capabilities & BCMA_CC_CAP_SPROM))
-		return -ENOENT;
+	if (!bcma_sprom_ext_available(bus)) {
+		/*
+		 * External SPROM takes precedence so check
+		 * on-chip OTP only when no external SPROM
+		 * is present.
+		 */
+		if (!bcma_sprom_onchip_available(bus))
+			return -ENOENT;
 
-	if (bus->drv_cc.core->id.rev >= 32) {
-		sromctrl = bcma_read32(bus->drv_cc.core, BCMA_CC_SROM_CONTROL);
-		if (!(sromctrl & BCMA_CC_SROM_CONTROL_PRESENT))
+		/* determine offset */
+		offset = bcma_sprom_onchip_offset(bus);
+		if (!offset)
 			return -ENOENT;
 	}
 
@@ -273,11 +372,6 @@ int bcma_sprom_get(struct bcma_bus *bus)
 	if (bus->chipinfo.id == 0x4331)
 		bcma_chipco_bcm4331_ext_pa_lines_ctl(&bus->drv_cc, false);
 
-	/* Most cards have SPROM moved by additional offset 0x30 (48 dwords).
-	 * According to brcm80211 this applies to cards with PCIe rev >= 6
-	 * TODO: understand this condition and use it */
-	offset = (bus->chipinfo.id == 0x4331) ? BCMA_CC_SPROM :
-		BCMA_CC_SPROM_PCIE6;
 	pr_debug("SPROM offset 0x%x\n", offset);
 	bcma_sprom_read(bus, offset, sprom);
 
diff --git a/include/linux/bcma/bcma_driver_chipcommon.h b/include/linux/bcma/bcma_driver_chipcommon.h
index e72938b..d963510 100644
--- a/include/linux/bcma/bcma_driver_chipcommon.h
+++ b/include/linux/bcma/bcma_driver_chipcommon.h
@@ -56,6 +56,9 @@
 #define	 BCMA_CC_OTPS_HW_PROTECT	0x00000001
 #define	 BCMA_CC_OTPS_SW_PROTECT	0x00000002
 #define	 BCMA_CC_OTPS_CID_PROTECT	0x00000004
+#define  BCMA_CC_OTPS_GU_PROG_IND	0x00000F00	/* General Use programmed indication */
+#define  BCMA_CC_OTPS_GU_PROG_IND_SHIFT	8
+#define  BCMA_CC_OTPS_GU_PROG_HW	0x00000100	/* HW region programmed */
 #define BCMA_CC_OTPC			0x0014		/* OTP control */
 #define	 BCMA_CC_OTPC_RECWAIT		0xFF000000
 #define	 BCMA_CC_OTPC_PROGWAIT		0x00FFFF00
@@ -72,6 +75,8 @@
 #define	 BCMA_CC_OTPP_READ		0x40000000
 #define	 BCMA_CC_OTPP_START		0x80000000
 #define	 BCMA_CC_OTPP_BUSY		0x80000000
+#define BCMA_CC_OTPL			0x001C		/* OTP layout */
+#define  BCMA_CC_OTPL_GURGN_OFFSET	0x00000FFF	/* offset of general use region */
 #define BCMA_CC_IRQSTAT			0x0020
 #define BCMA_CC_IRQMASK			0x0024
 #define	 BCMA_CC_IRQ_GPIO		0x00000001	/* gpio intr */
@@ -79,6 +84,10 @@
 #define	 BCMA_CC_IRQ_WDRESET		0x80000000	/* watchdog reset occurred */
 #define BCMA_CC_CHIPCTL			0x0028		/* Rev >= 11 only */
 #define BCMA_CC_CHIPSTAT		0x002C		/* Rev >= 11 only */
+#define  BCMA_CC_CHIPST_4313_SPROM_PRESENT	1
+#define  BCMA_CC_CHIPST_4313_OTP_PRESENT	2
+#define  BCMA_CC_CHIPST_4331_SPROM_PRESENT	2
+#define	 BCMA_CC_CHIPST_4331_OTP_PRESENT	4
 #define BCMA_CC_JCMD			0x0030		/* Rev >= 10 only */
 #define  BCMA_CC_JCMD_START		0x80000000
 #define  BCMA_CC_JCMD_BUSY		0x80000000
-- 
1.7.5.4