RE: [PATCH v2] tpm: Enable CLKRUN protocol for Braswell systems

["Shaikh, Azhar" <azhar.shaikh@intel.com>]

> -----Original Message-----
> From: Jarkko Sakkinen [mailto:jarkko.sakkinen@linux.intel.com]
> Sent: Monday, June 5, 2017 6:32 AM
> To: Shaikh, Azhar <azhar.shaikh@intel.com>
> Cc: jgunthorpe@obsidianresearch.com; tpmdd-devel@lists.sourceforge.net;
> linux-kernel@vger.kernel.org; linux-security-module@vger.kernel.org
> Subject: Re: [PATCH v2] tpm: Enable CLKRUN protocol for Braswell systems
> 
> On Thu, Jun 01, 2017 at 07:04:04PM -0700, Azhar Shaikh wrote:
> > To overcome a hardware limitation on Intel Braswell systems, disable
> > CLKRUN protocol during TPM transactions and re-enable once the
> > transaction is completed.
> >
> > Signed-off-by: Azhar Shaikh <azhar.shaikh@intel.com>
> > ---
> > Changes from v1:
> > - Add CONFIG_X86 around disable_lpc_clk_run () and
> > enable_lpc_clk_run() to avoid
> > - build breakage on architectures which do not implement
> > kmap_atomic_pfn()
> >
> >  drivers/char/tpm/tpm.h     | 20 ++++++++++
> >  drivers/char/tpm/tpm_tis.c | 94
> > ++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 114 insertions(+)
> >
> > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index
> > 4b4c8dee3096..98032a22317e 100644
> > --- a/drivers/char/tpm/tpm.h
> > +++ b/drivers/char/tpm/tpm.h
> > @@ -36,6 +36,10 @@
> >  #include <linux/highmem.h>
> >  #include <crypto/hash_info.h>
> >
> > +#ifdef CONFIG_X86
> > +#include <asm/intel-family.h>
> > +#endif
> 
> #ifdef's are not necessary here.

If the #ifdef's are not present, on non-Intel architectures, intel-family.h file is not found during compile time.

> 
> > +
> >  enum tpm_const {
> >  	TPM_MINOR = 224,	/* officially assigned */
> >  	TPM_BUFSIZE = 4096,
> > @@ -436,6 +440,22 @@ struct tpm_buf {
> >  	u8 *data;
> >  };
> >
> > +#define INTEL_LEGACY_BLK_BASE_ADDR	0xFED08000
> > +#define LPC_CNTRL_REG_OFFSET		0x84
> > +#define LPC_CLKRUN_EN			(1 << 2)
> > +
> > +#ifdef CONFIG_X86
> > +static inline bool is_bsw(void)
> > +{
> > +	return ((boot_cpu_data.x86_model ==
> INTEL_FAM6_ATOM_AIRMONT) ? 1 :
> > +0); } #else static inline bool is_bsw(void) {
> > +	return false;
> > +}
> > +#endif
> 
> Move these to tpm_tis.c right before disable_lpc_clk_run().

Ok, will do.

> 
> > +
> >  static inline int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32
> > ordinal)  {
> >  	struct tpm_input_header *head;
> > diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
> > index c7e1384f1b08..0c1496340a18 100644
> > --- a/drivers/char/tpm/tpm_tis.c
> > +++ b/drivers/char/tpm/tpm_tis.c
> > @@ -89,13 +89,79 @@ static inline int is_itpm(struct acpi_device *dev)
> > }  #endif
> >
> > +#ifdef CONFIG_X86
> > +/**
> > + * disable_lpc_clk_run() - clear LPC CLKRUN_EN i.e. clocks will be
> > +free running  */ static void disable_lpc_clk_run(void) {
> > +	u32 clkrun_val;
> > +	void __iomem *ilb_base_addr = NULL;
> > +
> > +	ilb_base_addr = (void __iomem *)
> > +		kmap_atomic_pfn(INTEL_LEGACY_BLK_BASE_ADDR >>
> PAGE_SHIFT);
> > +
> > +	clkrun_val = ioread32(ilb_base_addr + LPC_CNTRL_REG_OFFSET);
> > +
> > +	/* Disable LPC CLKRUN# */
> > +	clkrun_val &= ~LPC_CLKRUN_EN;
> > +	iowrite32(clkrun_val, ilb_base_addr + LPC_CNTRL_REG_OFFSET);
> > +
> > +	kunmap_atomic(ilb_base_addr);
> > +	/*
> > +	 * Write any random value on port 0x80 which is on LPC, to make
> > +	 * sure LPC clock is running before sending any TPM command.
> > +	 */
> > +	outb(0x80, 0xCC);
> > +}
> 
> You said that this code does not work compared to a version that does only
> static ioremap.
> 
> I compared this to the other version. One of the major differences is that
> outb() is done before releasing the mapping. Don't know or understand what
> difference that would make but it is a semantic difference.
> 
I tried unmapping after outb() and wmb(), still code does not work.

> Another observation is that should you have wmb() before outb() to make
> sure that all the write operations are complete?
> 
I think you meant to say add wmb() 'after' outb() and not before.

> > +
> > +/**
> > + * enable_lpc_clk_run() - set LPC CLKRUN_EN i.e. clocks can be turned
> > +off  */ static void enable_lpc_clk_run(void) {
> > +	u32 clkrun_val;
> > +	void __iomem *ilb_base_addr = NULL;
> > +
> > +	ilb_base_addr = (void __iomem *)
> > +		kmap_atomic_pfn(INTEL_LEGACY_BLK_BASE_ADDR >>
> PAGE_SHIFT);
> > +
> > +	clkrun_val = ioread32(ilb_base_addr + LPC_CNTRL_REG_OFFSET);
> > +
> > +	/* Enable LPC CLKRUN# */
> > +	clkrun_val |= LPC_CLKRUN_EN;
> > +	iowrite32(clkrun_val, ilb_base_addr + LPC_CNTRL_REG_OFFSET);
> > +
> > +	kunmap_atomic(ilb_base_addr);
> > +	/*
> > +	 * Write any random value on port 0x80 which is on LPC, to make
> > +	 * sure LPC clock is running before sending any TPM command.
> > +	 */
> > +	outb(0x80, 0xCC);
> > +}
> > +#else
> > +static void disable_lpc_clk_run(void) { } static void
> > +enable_lpc_clk_run(void) { } #endif
> > +
> >  static int tpm_tcg_read_bytes(struct tpm_tis_data *data, u32 addr, u16
> len,
> >  			      u8 *result)
> >  {
> >  	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> >
> > +	if (is_bsw())
> > +		disable_lpc_clk_run();
> 
> Do is_bsw() instead inside so that this can be unconditionally called.
> 

Ok, will do.

> > +
> >  	while (len--)
> >  		*result++ = ioread8(phy->iobase + addr);
> > +
> > +	if (is_bsw())
> > +		enable_lpc_clk_run();
> > +
> >  	return 0;
> >  }
> >
> > @@ -104,8 +170,15 @@ static int tpm_tcg_write_bytes(struct
> > tpm_tis_data *data, u32 addr, u16 len,  {
> >  	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> >
> > +	if (is_bsw())
> > +		disable_lpc_clk_run();
> > +
> >  	while (len--)
> >  		iowrite8(*value++, phy->iobase + addr);
> > +
> > +	if (is_bsw())
> > +		enable_lpc_clk_run();
> > +
> >  	return 0;
> >  }
> >
> > @@ -113,7 +186,14 @@ static int tpm_tcg_read16(struct tpm_tis_data
> > *data, u32 addr, u16 *result)  {
> >  	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> >
> > +	if (is_bsw())
> > +		disable_lpc_clk_run();
> > +
> >  	*result = ioread16(phy->iobase + addr);
> > +
> > +	if (is_bsw())
> > +		enable_lpc_clk_run();
> > +
> >  	return 0;
> >  }
> >
> > @@ -121,7 +201,14 @@ static int tpm_tcg_read32(struct tpm_tis_data
> > *data, u32 addr, u32 *result)  {
> >  	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> >
> > +	if (is_bsw())
> > +		disable_lpc_clk_run();
> > +
> >  	*result = ioread32(phy->iobase + addr);
> > +
> > +	if (is_bsw())
> > +		enable_lpc_clk_run();
> > +
> >  	return 0;
> >  }
> >
> > @@ -129,7 +216,14 @@ static int tpm_tcg_write32(struct tpm_tis_data
> > *data, u32 addr, u32 value)  {
> >  	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> >
> > +	if (is_bsw())
> > +		disable_lpc_clk_run();
> > +
> >  	iowrite32(value, phy->iobase + addr);
> > +
> > +	if (is_bsw())
> > +		enable_lpc_clk_run();
> > +
> >  	return 0;
> >  }
> >
> > --
> > 1.9.1
> >
> 
> /Jarkko