On Wed, Dec 02, 2020 at 12:58:05PM +0200, Adrian Ratiu wrote: > From: "[email protected]" <[email protected]> > > Add TPM 2.0 compatible I2C interface for chips with cr50 firmware. > > The firmware running on the currently supported H1 MCU requires a > special driver to handle its specific protocol, and this makes it > unsuitable to use tpm_tis_core_* and instead it must implement the > underlying TPM protocol similar to the other I2C TPM drivers. > > - All 4 bytes of status register must be read/written at once. > - FIFO and burst count is limited to 63 and must be drained by AP. > - Provides an interrupt to indicate when read response data is ready > and when the TPM is finished processing write data. > > This driver is based on the existing infineon I2C TPM driver, which > most closely matches the cr50 i2c protocol behavior. > > Cc: Helen Koike <[email protected]> > Cc: Jarkko Sakkinen <[email protected]> > Cc: Ezequiel Garcia <[email protected]> > Signed-off-by: Duncan Laurie <[email protected]> > [[email protected]: Depend on i2c even if it's a module, replace > boilier plate with SPDX tag, drop asm/byteorder.h include, simplify > return from probe] > Signed-off-by: Stephen Boyd <[email protected]> > Signed-off-by: Fabien Lahoudere <[email protected]> > Signed-off-by: Adrian Ratiu <[email protected]> > --- > Changes in v4: > - Replace force_release enum with defines (Jarkko) > > Changes in v3: > - Misc small fixes (typos/renamings, comments, default values) > - Moved i2c_write memcpy before lock to minimize critical section (Helen) > - Dropped priv->locality because it stored a constant value (Helen) > - Many kdoc, function name and style fixes in general (Jarkko) > - Kept the force release enum instead of defines or bool (Ezequiel) > > Changes in v2: > - Various small fixes all over (reorder includes, MAX_BUFSIZE, comments, > etc) > - Reworked return values of i2c_wait_tpm_ready() to fix timeout mis-handling > so ret == 0 now means success, the wait period jiffies is ignored because that > number is meaningless and return a proper timeout error in case jiffies == 0. > - Make i2c default to 1 message per transfer (requested by Helen) > - Move -EIO error reporting to transfer function to cleanup transfer() > itself > and its R/W callers > - Remove magic value hardcodings and introduce enum force_release. > > Applies on next-20201201, tested on Chromebook EVE. > --- > drivers/char/tpm/Kconfig | 10 + > drivers/char/tpm/Makefile | 2 + > drivers/char/tpm/tpm_tis_i2c_cr50.c | 767 ++++++++++++++++++++++++++++ > 3 files changed, 779 insertions(+) > create mode 100644 drivers/char/tpm/tpm_tis_i2c_cr50.c > > diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig > index a18c314da211..4308f9ca7a43 100644 > --- a/drivers/char/tpm/Kconfig > +++ b/drivers/char/tpm/Kconfig > @@ -86,6 +86,16 @@ config TCG_TIS_SYNQUACER > To compile this driver as a module, choose M here; > the module will be called tpm_tis_synquacer. > > +config TCG_TIS_I2C_CR50 > + tristate "TPM Interface Specification 2.0 Interface (I2C - CR50)" > + depends on I2C > + select TCG_CR50 > + help > + This is a driver for the Google cr50 I2C TPM interface which is a > + custom microcontroller and requires a custom i2c protocol interface > + to handle the limitations of the hardware. To compile this driver > + as a module, choose M here; the module will be called > tcg_tis_i2c_cr50. > + > config TCG_TIS_I2C_ATMEL > tristate "TPM Interface Specification 1.2 Interface (I2C - Atmel)" > depends on I2C > diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile > index 84db4fb3a9c9..66d39ea6bd10 100644 > --- a/drivers/char/tpm/Makefile > +++ b/drivers/char/tpm/Makefile > @@ -27,6 +27,8 @@ obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi.o > tpm_tis_spi-y := tpm_tis_spi_main.o > tpm_tis_spi-$(CONFIG_TCG_TIS_SPI_CR50) += tpm_tis_spi_cr50.o > > +obj-$(CONFIG_TCG_TIS_I2C_CR50) += tpm_tis_i2c_cr50.o > + > obj-$(CONFIG_TCG_TIS_I2C_ATMEL) += tpm_i2c_atmel.o > obj-$(CONFIG_TCG_TIS_I2C_INFINEON) += tpm_i2c_infineon.o > obj-$(CONFIG_TCG_TIS_I2C_NUVOTON) += tpm_i2c_nuvoton.o > diff --git a/drivers/char/tpm/tpm_tis_i2c_cr50.c > b/drivers/char/tpm/tpm_tis_i2c_cr50.c > new file mode 100644 > index 000000000000..a374853a3b4b > --- /dev/null > +++ b/drivers/char/tpm/tpm_tis_i2c_cr50.c > @@ -0,0 +1,767 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright 2016 Google Inc.
Should be 2020. > + * > + * Based on Linux Kernel TPM driver by > + * Peter Huewe <[email protected]> > + * Copyright (C) 2011 Infineon Technologies Not sure how this was derived. > + * > + * cr50 is a firmware for H1 secure modules that requires special > + * handling for the I2C interface. > + * > + * - Use an interrupt for transaction status instead of hardcoded delays. > + * - Must use write+wait+read read protocol. > + * - All 4 bytes of status register must be read/written at once. > + * - Burst count max is 63 bytes, and burst count behaves slightly > differently > + * than other I2C TPMs. > + * - When reading from FIFO the full burstcnt must be read instead of just > + * reading header and determining the remainder. > + */ > + > +#include <linux/acpi.h> > +#include <linux/completion.h> > +#include <linux/i2c.h> > +#include <linux/interrupt.h> > +#include <linux/module.h> > +#include <linux/pm.h> > +#include <linux/slab.h> > +#include <linux/wait.h> > + > +#include "tpm_tis_core.h" > + > +#define TPM_CR50_MAX_BUFSIZE 64 > +#define TPM_CR50_TIMEOUT_SHORT_MS 2 /* Short timeout during > transactions */ > +#define TPM_CR50_TIMEOUT_NOIRQ_MS 20 /* Timeout for TPM ready > without IRQ */ > +#define TPM_CR50_I2C_DID_VID 0x00281ae0L /* Device and vendor ID reg > value */ > +#define TPM_CR50_I2C_MAX_RETRIES 3 /* Max retries due to I2C > errors */ > +#define TPM_CR50_I2C_RETRY_DELAY_LO 55 /* Min usecs between retries on > I2C */ > +#define TPM_CR50_I2C_RETRY_DELAY_HI 65 /* Max usecs between retries on > I2C */ > + > +#define TPM_I2C_ACCESS(l) (0x0000 | ((l) << 4)) > +#define TPM_I2C_STS(l) (0x0001 | ((l) << 4)) > +#define TPM_I2C_DATA_FIFO(l) (0x0005 | ((l) << 4)) > +#define TPM_I2C_DID_VID(l) (0x0006 | ((l) << 4)) > + > +#define TPM_I2C_CR50_NO_FORCE 0 > +#define TPM_I2C_CR50_FORCE 1 No need for these. > + > +/** > + * struct tpm_i2c_cr50_priv_data - Driver private data. > + * @irq: Irq number used for this chip. > + * If irq <= 0, then a fixed timeout is used instead of waiting for > irq. > + * @tpm_ready: Struct used by irq handler to signal R/W readiness. > + * @buf: Buffer used for i2c writes, with i2c address prepended to content. Not properly aligned. https://www.kernel.org/doc/Documentation/kernel-doc-nano-HOWTO.txt > + */ > +struct tpm_i2c_cr50_priv_data { > + int irq; > + struct completion tpm_ready; > + u8 buf[TPM_CR50_MAX_BUFSIZE]; > +}; > + > +/** > + * tpm_cr50_i2c_int_handler() - cr50 interrupt handler. > + * @dummy: Unused parameter. > + * @dev_id: TPM chip information. This is alignment everywhere. Why the parameter is called "dev_id" anyway? > + * > + * The cr50 interrupt handler signals waiting threads that the > + * interrupt has been asserted. It does not do any interrupt triggered > + * processing but is instead used to avoid fixed delays. > + */ > +static irqreturn_t tpm_cr50_i2c_int_handler(int dummy, void *dev_id) > +{ > + struct tpm_chip *chip = dev_id; > + struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev); > + > + complete(&priv->tpm_ready); > + > + return IRQ_HANDLED; > +} > + > +/** > + * tpm_cr50_i2c_wait_tpm_ready() - Wait for tpm to signal ready. > + * @chip: TPM chip information. > + * > + * Wait for completion interrupt if available, otherwise use a fixed > + * delay for the TPM to be ready. > + * > + * Return: 0 for success or timeout error number. > + */ > +static int tpm_cr50_i2c_wait_tpm_ready(struct tpm_chip *chip) > +{ > + struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev); > + > + /* Use a safe fixed delay if interrupt is not supported */ > + if (priv->irq <= 0) { > + msleep(TPM_CR50_TIMEOUT_NOIRQ_MS); > + return 0; > + } > + > + /* Wait for interrupt to indicate TPM is ready to respond */ > + if (!wait_for_completion_timeout(&priv->tpm_ready, > + msecs_to_jiffies(chip->timeout_a))) { > + dev_warn(&chip->dev, "Timeout waiting for TPM ready\n"); > + return -ETIMEDOUT; > + } > + > + return 0; > +} > + > +/** > + * tpm_cr50_i2c_enable_tpm_irq() - Enable TPM irq. > + * @chip: TPM chip information. > + */ > +static void tpm_cr50_i2c_enable_tpm_irq(struct tpm_chip *chip) > +{ > + struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev); > + > + if (priv->irq > 0) { > + reinit_completion(&priv->tpm_ready); > + enable_irq(priv->irq); > + } > +} > + > +/** > + * tpm_cr50_i2c_disable_tpm_irq() - Disable TPM irq. > + * @chip: TPM chip information. > + */ > +static void tpm_cr50_i2c_disable_tpm_irq(struct tpm_chip *chip) > +{ > + struct tpm_i2c_cr50_priv_data *priv = dev_get_drvdata(&chip->dev); > + > + if (priv->irq > 0) > + disable_irq(priv->irq); > +} > + > +/** > + * tpm_cr50_i2c_transfer_message() - Transfer a message over i2c. > + * @dev: Device information. > + * @adapter: I2C adapter. > + * @msg:Mmessage to transfer. Alignment etc. > + * > + * Call unlocked i2c transfer routine with the provided parameters and > + * retry in case of bus errors. > + * > + * Return: 0 on success, otherwise negative errno. > + */ > +static int tpm_cr50_i2c_transfer_message(struct device *dev, > + struct i2c_adapter *adapter, > + struct i2c_msg *msg) > +{ > + int rc; > + unsigned int try; Opposite order would be more readable (reverse christmas tree). > + > + for (try = 0; try < TPM_CR50_I2C_MAX_RETRIES; try++) { > + rc = __i2c_transfer(adapter, msg, 1); > + if (rc == 1) > + return 0; /* Successfully transferred the message */ > + if (try) > + dev_warn(dev, "i2c transfer failed (attempt %d/%d): > %d\n", > + try + 1, TPM_CR50_I2C_MAX_RETRIES, rc); > + usleep_range(TPM_CR50_I2C_RETRY_DELAY_LO, > + TPM_CR50_I2C_RETRY_DELAY_HI); Can be probably put into one line without checkpatch.pl complaining. Giving up at this point. /Jarkko
