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Commit 80546ac5 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc/powernv: Add support for indirect XSCOM via debugfs 



Indirect XSCOM addresses normally have the top bit set (of the 64-bit
address). This doesn't work via the normal debugfs interface, so we use
a different encoding, which we need to convert before calling OPAL.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent cda13552

arch/powerpc/platforms/powernv/opal-xscom.c

+23 −0
Original line number Original line Diff line number Diff line
@@ -71,11 +71,33 @@ static int opal_xscom_err_xlate(int64_t rc) 
	}

	}

}

}





static u64 opal_scom_unmangle(u64 reg)

{

	/*

	 * XSCOM indirect addresses have the top bit set. Additionally

	 * the reset of the top 3 nibbles is always 0.

	 *

	 * Because the debugfs interface uses signed offsets and shifts

	 * the address left by 3, we basically cannot use the top 4 bits

	 * of the 64-bit address, and thus cannot use the indirect bit.

	 *

	 * To deal with that, we support the indirect bit being in bit

	 * 4 (IBM notation) instead of bit 0 in this API, we do the

	 * conversion here. To leave room for further xscom address

	 * expansion, we only clear out the top byte

	 *

	 */

	if (reg & (1ull << 59))

		reg = (reg & ~(0xffull << 56)) | (1ull << 63);

	return reg;

}



static int opal_scom_read(scom_map_t map, u64 reg, u64 *value)

static int opal_scom_read(scom_map_t map, u64 reg, u64 *value)

{

{

	struct opal_scom_map *m = map;

	struct opal_scom_map *m = map;

	int64_t rc;

	int64_t rc;





	reg = opal_scom_unmangle(reg);

	rc = opal_xscom_read(m->chip, m->addr + reg, (uint64_t *)__pa(value));

	rc = opal_xscom_read(m->chip, m->addr + reg, (uint64_t *)__pa(value));

	return opal_xscom_err_xlate(rc);

	return opal_xscom_err_xlate(rc);

}

}
@@ -85,6 +107,7 @@ static int opal_scom_write(scom_map_t map, u64 reg, u64 value) 
	struct opal_scom_map *m = map;

	struct opal_scom_map *m = map;

	int64_t rc;

	int64_t rc;





	reg = opal_scom_unmangle(reg);

	rc = opal_xscom_write(m->chip, m->addr + reg, value);

	rc = opal_xscom_write(m->chip, m->addr + reg, value);

	return opal_xscom_err_xlate(rc);

	return opal_xscom_err_xlate(rc);

}

}