[PATCH 4.15 122/146] tpm: only attempt to disable the LPC CLKRUN if is already enabled

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Javier Martinez Canillas <javierm@xxxxxxxxxx>

commit 6c9f0ce0dffe64da2204f38b0fd90f3ae2a8903c upstream.

Commit 5e572cab92f0 ("tpm: Enable CLKRUN protocol for Braswell systems")
added logic in the TPM TIS driver to disable the Low Pin Count CLKRUN
signal during TPM transactions.

Unfortunately this breaks other devices that are attached to the LPC bus
like for example PS/2 mouse and keyboards.

One flaw with the logic is that it assumes that the CLKRUN is always
enabled, and so it unconditionally enables it after a TPM transaction.

But it could be that the CLKRUN# signal was already disabled in the LPC
bus and so after the driver probes, CLKRUN_EN will remain enabled which
may break other devices that are attached to the LPC bus but don't have
support for the CLKRUN protocol.

Fixes: 5e572cab92f0 ("tpm: Enable CLKRUN protocol for Braswell systems")
Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Tested-by: James Ettle <james@xxxxxxxxxxxx>
Tested-by: Jeffery Miller <jmiller@xxxxxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/char/tpm/tpm_tis_core.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -694,7 +694,8 @@ static void tpm_tis_clkrun_enable(struct
 	struct tpm_tis_data *data = dev_get_drvdata(&chip->dev);
 	u32 clkrun_val;
 
-	if (!IS_ENABLED(CONFIG_X86) || !is_bsw())
+	if (!IS_ENABLED(CONFIG_X86) || !is_bsw() ||
+	    !data->ilb_base_addr)
 		return;
 
 	if (value) {
@@ -751,6 +752,7 @@ int tpm_tis_core_init(struct device *dev
 		      acpi_handle acpi_dev_handle)
 {
 	u32 vendor, intfcaps, intmask;
+	u32 clkrun_val;
 	u8 rid;
 	int rc, probe;
 	struct tpm_chip *chip;
@@ -776,6 +778,13 @@ int tpm_tis_core_init(struct device *dev
 					ILB_REMAP_SIZE);
 		if (!priv->ilb_base_addr)
 			return -ENOMEM;
+
+		clkrun_val = ioread32(priv->ilb_base_addr + LPC_CNTRL_OFFSET);
+		/* Check if CLKRUN# is already not enabled in the LPC bus */
+		if (!(clkrun_val & LPC_CLKRUN_EN)) {
+			iounmap(priv->ilb_base_addr);
+			priv->ilb_base_addr = NULL;
+		}
 	}
 
 	if (chip->ops->clk_enable != NULL)