Re: [PATCH v2] char: tpm: add i2c driver for cr50

[Adrian Ratiu <adrian.ratiu@collabora.com>]

On Tue, 24 Nov 2020, Jarkko Sakkinen <jarkko@kernel.org> wrote:
> On Fri, Nov 20, 2020 at 07:23:45PM +0200, Adrian Ratiu wrote: 
>> From: "dlaurie@chromium.org" <dlaurie@chromium.org>  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 byes 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 
>> <helen.koike@collabora.com> Signed-off-by: Duncan Laurie 
>> <dlaurie@chromium.org> [swboyd@chromium.org: 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 <swboyd@chromium.org> 
>> Signed-off-by: Fabien Lahoudere 
>> <fabien.lahoudere@collabora.com> Signed-off-by: Adrian Ratiu 
>> <adrian.ratiu@collabora.com> --- 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. 
>>  v1 posted at https://lkml.org/lkml/2020/2/25/349  Applies on 
>> next-20201120, tested on Chromebook EVE.  --- 
>>  drivers/char/tpm/Kconfig            |  10 + 
>>  drivers/char/tpm/Makefile           |   2 + 
>>  drivers/char/tpm/tpm_tis_i2c_cr50.c | 768 
>>  ++++++++++++++++++++++++++++ 3 files changed, 780 
>>  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..37555dafdca0 --- /dev/null +++ 
>> b/drivers/char/tpm/tpm_tis_i2c_cr50.c @@ -0,0 +1,768 @@ +// 
>> SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2016 Google 
>> Inc.  + * + * Based on Linux Kernel TPM driver by + * Peter 
>> Huewe <peter.huewe@infineon.com> + * Copyright (C) 2011 
>> Infineon Technologies + */ + +/* + * 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 CR50_MAX_BUFSIZE	64 
>> +#define CR50_TIMEOUT_SHORT_MS	2	/* Short timeout 
>> during transactions */ +#define CR50_TIMEOUT_NOIRQ_MS	20 
>> /* Timeout for TPM ready without IRQ */ +#define 
>> CR50_I2C_DID_VID	0x00281ae0L +#define CR50_I2C_MAX_RETRIES 
>> 3	/* Max retries due to I2C errors */ +#define 
>> CR50_I2C_RETRY_DELAY_LO	55	/* Min usecs between 
>> retries on I2C */ +#define CR50_I2C_RETRY_DELAY_HI	65	/* 
>> Max usecs between retries on I2C */ 
> 
> CR50_ -> TPM_CR50_ 
> 
>> + +#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)) + +struct priv_data 
>> { +	int irq; +	int locality; +	struct completion 
>> tpm_ready; +	u8 buf[CR50_MAX_BUFSIZE]; +}; 
> 
> tpm_i2c_cr50_priv_data 
> 
>> + +enum force_release { +	CR50_NO_FORCE = 0x0, +	CR50_FORCE 
>> = 0x1, +}; 
> 
> I'd just  
> 
> #define TPM_I2C_CR50_NO_FORCE	0 #define TPM_I2C_CR50_FORCE	1 
> 
>> + +/* + * The cr50 interrupt handler just signals waiting 
>> threads that the + * interrupt was asserted.  It does not do 
>> any processing triggered + * by interrupts but is instead used 
>> to avoid fixed delays.  + * + * @dummy: unuesed parameter + * 
>> @dev_id: TPM chip information + */ 
> 
> Please review for kdoc: 
> 
> https://www.kernel.org/doc/Documentation/kernel-doc-nano-HOWTO.txt 
> 
>> +static irqreturn_t cr50_i2c_int_handler(int dummy, void 
>> *dev_id) 
> 
> cr50 -> tpm_i2c_cr50_ 
> 
>> +{ +	struct tpm_chip *chip = dev_id; +	struct priv_data 
>> *priv = dev_get_drvdata(&chip->dev); + + 
>> complete(&priv->tpm_ready); + +	return IRQ_HANDLED; +} + 
>> +/* + * Wait for completion interrupt if available, otherwise 
>> use a fixed + * delay for the TPM to be ready.  + * + * @chip: 
>> TPM chip information + * + * Returns 0 for success, negative 
>> number for timeout + */ +static int 
>> cr50_i2c_wait_tpm_ready(struct tpm_chip *chip) 
> 
> Ditto. 
> 
>> +{ +	struct priv_data *priv = dev_get_drvdata(&chip->dev); + + 
>> /* Use a safe fixed delay if interrupt is not supported */ +	if 
>> (priv->irq <= 0) { +		msleep(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; +} + +/* + * 
>> cr50_i2c_enable_tpm_irq - enable TPM irq + * + * @chip: TPM 
>> chip information + */ +static void 
>> cr50_i2c_enable_tpm_irq(struct tpm_chip *chip) +{ +	struct 
>> priv_data *priv = dev_get_drvdata(&chip->dev); + +	if 
>> (priv->irq > 0) { + 
>> reinit_completion(&priv->tpm_ready); + 
>> enable_irq(priv->irq); +	} +} + +/* + * 
>> cr50_i2c_disable_tpm_irq - disable TPM irq + * + * @chip: TPM 
>> chip information + */ +static void 
>> cr50_i2c_disable_tpm_irq(struct tpm_chip *chip) +{ +	struct 
>> priv_data *priv = dev_get_drvdata(&chip->dev); + +	if 
>> (priv->irq > 0) +		disable_irq(priv->irq); +} + +/* + 
>> * cr50_i2c_transfer_message - transfer a message over i2c + * + 
>> * @dev: device information + * @adapter: i2c adapter + * @msg: 
>> message to transfer + * + * Call unlocked i2c transfer routine 
>> with the provided parameters and retry + * in case of bus 
>> errors. Returns 0 on success, otherwise negative errno.  + */ 
>> +static int cr50_i2c_transfer_message(struct device *dev, + 
>> struct i2c_adapter *adapter, + 
>> struct i2c_msg *msg) +{ +	int rc = 0; +	unsigned int try; 
>> + +	for (try = 0; try < 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, CR50_I2C_MAX_RETRIES, rc); + 
>> usleep_range(CR50_I2C_RETRY_DELAY_LO, CR50_I2C_RETRY_DELAY_HI); 
>> +	} + +	return -EIO; /* No i2c message transferred */ +} + 
>> +/* + * cr50_i2c_read() - read from TPM register + * 
> 
> Not only wrong formatting but seems that these kdoc's have 
> differing formatting (no newline). 
> 
>> + * @chip: TPM chip information + * @addr: register address to 
>> read from + * @buffer: provided by caller + * @len: number of 
>> bytes to read + * + * 1) send register address byte 'addr' to 
>> the TPM + * 2) wait for TPM to indicate it is ready + * 3) read 
>> 'len' bytes of TPM response into the provided 'buffer' 
> 
> Please write proper sentences instead of lower-case (also 
> applies to parameters as you can see from kernel documentation). 
> 
>> + * + * Returns negative number for error, 0 for success.  + */ 
>> +static int cr50_i2c_read(struct tpm_chip *chip, u8 addr, u8 
>> *buffer, size_t len) +{ +	struct i2c_client *client = 
>> to_i2c_client(chip->dev.parent); +	struct i2c_msg msg1 = { + 
>> .addr = client->addr, +		.len = 1, + 
>> .buf = &addr +	}; +	struct i2c_msg msg2 = { + 
>> .addr = client->addr, +		.flags = I2C_M_RD, + 
>> .len = len, +		.buf = buffer +	}; +	int rc; + 
>> +	i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT); + +	/* 
>> Prepare for completion interrupt */ + 
>> cr50_i2c_enable_tpm_irq(chip); + +	/* Send the register 
>> address byte to the TPM */ +	rc = 
>> cr50_i2c_transfer_message(&chip->dev, client->adapter, &msg1); 
>> +	if (rc < 0) +		goto out; + +	/* Wait for TPM to 
>> be ready with response data */ +	rc = 
>> cr50_i2c_wait_tpm_ready(chip); +	if (rc < 0) + 
>> goto out; + +	/* Read response data from the TPM */ +	rc 
>> = cr50_i2c_transfer_message(&chip->dev, client->adapter, 
>> &msg2); + +out: +	cr50_i2c_disable_tpm_irq(chip); + 
>> i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT); + +	if 
>> (rc < 0) +		return rc; + +	return 0; +} + +/* + * 
>> cr50_i2c_write() - write to TPM register + * + * @chip: TPM 
>> chip information + * @addr: register address to write to + * 
>> @buffer: data to write + * @len: number of bytes to write + * + 
>> * 1) prepend the provided address to the provided data + * 2) 
>> send the address+data to the TPM + * 3) wait for TPM to 
>> indicate it is done writing + * + * Returns negative number for 
>> error, 0 for success.  + */ +static int cr50_i2c_write(struct 
>> tpm_chip *chip, u8 addr, u8 *buffer, + 
>> size_t len) +{ +	struct priv_data *priv = 
>> dev_get_drvdata(&chip->dev); +	struct i2c_client *client 
>> = to_i2c_client(chip->dev.parent); +	struct i2c_msg msg1 = { + 
>> .addr = client->addr, +		.len = len + 1, + 
>> .buf = priv->buf +	}; +	int rc; + +	if (len > 
>> CR50_MAX_BUFSIZE - 1) +		return -EINVAL; + + 
>> i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT); + +	/* Prepend 
>> the 'register address' to the buffer */ +	priv->buf[0] = 
>> addr; +	memcpy(priv->buf + 1, buffer, len); + +	/* Prepare 
>> for completion interrupt */ + 
>> cr50_i2c_enable_tpm_irq(chip); + +	/* Send write request 
>> buffer with address */ +	rc = 
>> cr50_i2c_transfer_message(&chip->dev, client->adapter, &msg1); 
>> +	if (rc < 0) +		goto out; + +	/* Wait for TPM to 
>> be ready, ignore timeout */ + 
>> cr50_i2c_wait_tpm_ready(chip); + +out: + 
>> cr50_i2c_disable_tpm_irq(chip); + 
>> i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT); + +	if 
>> (rc < 0) +		return rc; + +	return 0; +} + +/* + * 
>> cr50_check_locality - verify TPM locality + * + * @chip: TPM 
>> chip information + * + * Returns negative number for error, 0 
>> for success.  + */ +static int cr50_check_locality(struct 
>> tpm_chip *chip) +{ +	u8 mask = TPM_ACCESS_VALID | 
>> TPM_ACCESS_ACTIVE_LOCALITY; +	u8 buf; +	int rc; + 
>> +	rc = cr50_i2c_read(chip, TPM_I2C_ACCESS(0), &buf, 
>> sizeof(buf)); +	if (rc < 0) +		return rc; + +	if 
>> ((buf & mask) == mask) +		return 0; + +	return 
>> -EIO; +} + +/* + * cr50_release_locality - release TPM locality 
>> + * + * @chip: TPM chip information + * @force: flag to force 
>> release if set + */ +static void cr50_release_locality(struct 
>> tpm_chip *chip, +				  enum 
>> force_release force) +{ +	struct priv_data *priv = 
>> dev_get_drvdata(&chip->dev); +	u8 mask = TPM_ACCESS_VALID 
>> | TPM_ACCESS_REQUEST_PENDING; +	u8 addr = 
>> TPM_I2C_ACCESS(priv->locality); +	u8 buf; + +	if 
>> (cr50_i2c_read(chip, addr, &buf, sizeof(buf)) < 0) + 
>> return; + +	if (force || (buf & mask) == mask) { + 
>> buf = TPM_ACCESS_ACTIVE_LOCALITY; + 
>> cr50_i2c_write(chip, addr, &buf, sizeof(buf)); +	} + + 
>> priv->locality = 0; +} + +/* + * request_locality - request TPM 
>> locality + * + * @chip: TPM chip information + */ +static int 
>> request_locality(struct tpm_chip *chip) +{ +	struct priv_data 
>> *priv = dev_get_drvdata(&chip->dev); +	u8 buf = 
>> TPM_ACCESS_REQUEST_USE; +	unsigned long stop; +	int rc; + 
>> +	if (!cr50_check_locality(chip)) +		return 0; 
>> + +	rc = cr50_i2c_write(chip, TPM_I2C_ACCESS(0), &buf, 
>> sizeof(buf)); +	if (rc < 0) +		return rc; + + 
>> stop = jiffies + chip->timeout_a; +	do { +		if 
>> (!cr50_check_locality(chip)) { + 
>> priv->locality = 0; +			return 0; + 
>> } +		msleep(CR50_TIMEOUT_SHORT_MS); +	} while 
>> (time_before(jiffies, stop)); + +	return -ETIMEDOUT; +} + 
>> +/* + * cr50 requires all 4 bytes of status register to be read 
>> + * + * @chip: TPM chip information + * + * Returns TPM status 
>> + */ +static u8 cr50_i2c_tis_status(struct tpm_chip *chip) +{ + 
>> struct priv_data *priv = dev_get_drvdata(&chip->dev); +	u8 
>> buf[4]; + +	if (cr50_i2c_read(chip, 
>> TPM_I2C_STS(priv->locality), +			  buf, 
>> sizeof(buf)) < 0) +		return 0; +	return buf[0]; +} 
>> + +/* + * cr50 requires all 4 bytes of status register to be 
>> written + * + * @chip: TPM chip information + */ +static void 
>> cr50_i2c_tis_ready(struct tpm_chip *chip) +{ +	struct 
>> priv_data *priv = dev_get_drvdata(&chip->dev); +	u8 buf[4] 
>> = { TPM_STS_COMMAND_READY }; + +	cr50_i2c_write(chip, 
>> TPM_I2C_STS(priv->locality), buf, sizeof(buf)); + 
>> msleep(CR50_TIMEOUT_SHORT_MS); +} + +/* + * cr50 uses bytes 3:2 
>> of status register for burst count and + * all 4 bytes must be 
>> read + * + * @chip: TPM chip information + * @mask: status mask 
>> + * @burst: return value for burst + * @status: return value 
>> for statis + * + * Returns negative number for error, 0 for 
>> success.  + */ +static int cr50_i2c_wait_burststs(struct 
>> tpm_chip *chip, u8 mask, +				  size_t 
>> *burst, int *status) +{ +	struct priv_data *priv = 
>> dev_get_drvdata(&chip->dev); +	unsigned long stop; +	u8 
>> buf[4]; + +	/* wait for burstcount */ +	stop = jiffies + 
>> chip->timeout_b; +	do { +		if (cr50_i2c_read(chip, 
>> TPM_I2C_STS(priv->locality), + 
>> buf, sizeof(buf)) < 0) { + 
>> msleep(CR50_TIMEOUT_SHORT_MS); +			continue; 
>> +		} + +		*status = *buf; + 
>> *burst = le16_to_cpup((__le16 *)(buf + 1)); + +		if 
>> ((*status & mask) == mask && +		    *burst > 0 && 
>> *burst <= CR50_MAX_BUFSIZE - 1) +			return 0; 
>> + +		msleep(CR50_TIMEOUT_SHORT_MS); +	} while 
>> (time_before(jiffies, stop)); + +	dev_err(&chip->dev, 
>> "Timeout reading burst and status\n"); +	return -ETIMEDOUT; 
>> +} + +/* + * cr50_i2c_tis_recv - TPM reception callback + * + * 
>> @chip: TPM chip information + * @buf: reception buffer + * 
>> @buf_len: buffer length to read + * + * Returns negative number 
>> for error, number of bytes read for success.  + */ +static int 
>> cr50_i2c_tis_recv(struct tpm_chip *chip, u8 *buf, size_t 
>> buf_len) +{ +	struct priv_data *priv = 
>> dev_get_drvdata(&chip->dev); +	int status, rc; + 
>> size_t burstcnt, cur, len, expected; +	u8 addr = 
>> TPM_I2C_DATA_FIFO(priv->locality); +	u8 mask = TPM_STS_VALID | 
>> TPM_STS_DATA_AVAIL; + +	if (buf_len < TPM_HEADER_SIZE) + 
>> return -EINVAL; + +	rc = cr50_i2c_wait_burststs(chip, mask, 
>> &burstcnt, &status); +	if (rc < 0) +		goto 
>> out_err; + +	if (burstcnt > buf_len || burstcnt < 
>> TPM_HEADER_SIZE) { +		dev_err(&chip->dev, + 
>> "Unexpected burstcnt: %zu (max=%zu, min=%d)\n", + 
>> burstcnt, buf_len, TPM_HEADER_SIZE); +		rc = -EIO; 
>> +		goto out_err; +	} + +	/* Read first chunk of 
>> burstcnt bytes */ +	rc = cr50_i2c_read(chip, addr, buf, 
>> burstcnt); +	if (rc < 0) { +		dev_err(&chip->dev, "Read 
>> of first chunk failed\n"); +		goto out_err; +	} + +	/* 
>> Determine expected data in the return buffer */ +	expected = 
>> be32_to_cpup((__be32 *)(buf + 2)); +	if (expected > buf_len) { 
>> +		dev_err(&chip->dev, "Buffer too small to receive 
>> i2c data\n"); +		goto out_err; +	} + +	/* Now 
>> read the rest of the data */ +	cur = burstcnt; + 
>> while (cur < expected) { +		/* Read updated burst 
>> count and check status */ +		rc = 
>> cr50_i2c_wait_burststs(chip, mask, &burstcnt, &status); + 
>> if (rc < 0) +			goto out_err; + + 
>> len = min_t(size_t, burstcnt, expected - cur); +		rc 
>> = cr50_i2c_read(chip, addr, buf + cur, len); +		if 
>> (rc < 0) { +			dev_err(&chip->dev, "Read 
>> failed\n"); +			goto out_err; +		} 
>> + +		cur += len; +	} + +	/* Ensure TPM is done 
>> reading data */ +	rc = cr50_i2c_wait_burststs(chip, 
>> TPM_STS_VALID, &burstcnt, &status); +	if (rc < 0) + 
>> goto out_err; +	if (status & TPM_STS_DATA_AVAIL) { + 
>> dev_err(&chip->dev, "Data still available\n"); +		rc 
>> = -EIO; +		goto out_err; +	} + + 
>> cr50_release_locality(chip, CR50_NO_FORCE); +	return 
>> cur; + +out_err: +	/* Abort current transaction if still 
>> pending */ +	if (cr50_i2c_tis_status(chip) & 
>> TPM_STS_COMMAND_READY) +		cr50_i2c_tis_ready(chip); 
>> + +	cr50_release_locality(chip, CR50_NO_FORCE); +	return rc; 
>> +} + +/* + * cr50_i2c_tis_send - TPM emission callback + * + * 
>> @chip: TPM chip information + * @buf: buffer to send + * @len: 
>> buffer length + * + * Returns negative number for error, 0 for 
>> success.  + */ +static int cr50_i2c_tis_send(struct tpm_chip 
>> *chip, u8 *buf, size_t len) +{ +	struct priv_data *priv = 
>> dev_get_drvdata(&chip->dev); +	int rc, status; + 
>> size_t burstcnt, limit, sent = 0; +	u8 tpm_go[4] = { 
>> TPM_STS_GO }; +	unsigned long stop; + +	rc = 
>> request_locality(chip); +	if (rc < 0) +		return rc; 
>> + +	/* Wait until TPM is ready for a command */ +	stop = 
>> jiffies + chip->timeout_b; +	while (!(cr50_i2c_tis_status(chip) 
>> & TPM_STS_COMMAND_READY)) { +		if 
>> (time_after(jiffies, stop)) { +			rc = 
>> -ETIMEDOUT; +			goto out_err; +		} 
>> + +		cr50_i2c_tis_ready(chip); +	} + +	while (len 
>> > 0) { +		u8 mask = TPM_STS_VALID; + +		/* 
>> Wait for data if this is not the first chunk */ +		if 
>> (sent > 0) +			mask |= TPM_STS_DATA_EXPECT; + + 
>> /* Read burst count and check status */ +		rc = 
>> cr50_i2c_wait_burststs(chip, mask, &burstcnt, &status); + 
>> if (rc < 0) +			goto out_err; + + 
>> /* +		 * Use burstcnt - 1 to account for the address 
>> byte +		 * that is inserted by cr50_i2c_write() + 
>> */ +		limit = min_t(size_t, burstcnt - 1, len); + 
>> rc = cr50_i2c_write(chip, TPM_I2C_DATA_FIFO(priv->locality), + 
>> &buf[sent], limit); +		if (rc < 0) { + 
>> dev_err(&chip->dev, "Write failed\n"); + 
>> goto out_err; +		} + +		sent += limit; + 
>> len -= limit; +	} + +	/* Ensure TPM is not expecting 
>> more data */ +	rc = cr50_i2c_wait_burststs(chip, 
>> TPM_STS_VALID, &burstcnt, &status); +	if (rc < 0) + 
>> goto out_err; +	if (status & TPM_STS_DATA_EXPECT) { + 
>> dev_err(&chip->dev, "Data still expected\n"); +		rc 
>> = -EIO; +		goto out_err; +	} + +	/* Start the TPM 
>> command */ +	rc = cr50_i2c_write(chip, 
>> TPM_I2C_STS(priv->locality), tpm_go, + 
>> sizeof(tpm_go)); +	if (rc < 0) { + 
>> dev_err(&chip->dev, "Start command failed\n"); + 
>> goto out_err; +	} +	return 0; + +out_err: +	/* Abort 
>> current transaction if still pending */ +	if 
>> (cr50_i2c_tis_status(chip) & TPM_STS_COMMAND_READY) + 
>> cr50_i2c_tis_ready(chip); + + 
>> cr50_release_locality(chip, CR50_NO_FORCE); +	return rc; 
>> +} + +/* + * cr50_i2c_req_canceled - callback to notify a 
>> request cancel + * + * @chip: TPM chip information + * @status: 
>> status given by the cancel callback + * + * Return if command 
>> is ready or not + */ +static bool cr50_i2c_req_canceled(struct 
>> tpm_chip *chip, u8 status) +{ +	return (status == 
>> TPM_STS_COMMAND_READY); +} + +static const struct tpm_class_ops 
>> cr50_i2c = { +	.flags = TPM_OPS_AUTO_STARTUP, + 
>> .status = &cr50_i2c_tis_status, +	.recv = 
>> &cr50_i2c_tis_recv, +	.send = &cr50_i2c_tis_send, + 
>> .cancel = &cr50_i2c_tis_ready, +	.req_complete_mask = 
>> TPM_STS_DATA_AVAIL | TPM_STS_VALID, +	.req_complete_val 
>> = TPM_STS_DATA_AVAIL | TPM_STS_VALID, +	.req_canceled = 
>> &cr50_i2c_req_canceled, +}; + +static const struct 
>> i2c_device_id cr50_i2c_table[] = { +	{"cr50_i2c", 0}, +	{} 
>> +}; +MODULE_DEVICE_TABLE(i2c, cr50_i2c_table); + +#ifdef 
>> CONFIG_ACPI +static const struct acpi_device_id 
>> cr50_i2c_acpi_id[] = { +	{ "GOOG0005", 0 }, +	{} +}; 
>> +MODULE_DEVICE_TABLE(acpi, cr50_i2c_acpi_id); +#endif + +#ifdef 
>> CONFIG_OF +static const struct of_device_id of_cr50_i2c_match[] 
>> = { +	{ .compatible = "google,cr50", }, +	{} +}; 
>> +MODULE_DEVICE_TABLE(of, of_cr50_i2c_match); +#endif + +/* + * 
>> cr50_i2c_probe - driver prbe function + * + * @client: i2x 
>> client information + * @id: i2c device id + * + * Returns 
>> negative number for error, 0 for success.  + */ +static int 
>> cr50_i2c_probe(struct i2c_client *client, + 
>> const struct i2c_device_id *id) +{ +	struct device *dev = 
>> &client->dev; +	struct tpm_chip *chip; +	struct 
>> priv_data *priv; +	u8 buf[4]; +	u32 vendor; +	int rc; + 
>> +	if (!i2c_check_functionality(client->adapter, 
>> I2C_FUNC_I2C)) +		return -ENODEV; + +	chip = 
>> tpmm_chip_alloc(dev, &cr50_i2c); +	if (IS_ERR(chip)) + 
>> return PTR_ERR(chip); + +	priv = devm_kzalloc(dev, 
>> sizeof(*priv), GFP_KERNEL); +	if (!priv) + 
>> return -ENOMEM; + +	/* cr50 is a TPM 2.0 chip */ + 
>> chip->flags |= TPM_CHIP_FLAG_TPM2; +	chip->flags |= 
>> TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED; + +	/* Default 
>> timeouts */ +	chip->timeout_a = 
>> msecs_to_jiffies(TIS_SHORT_TIMEOUT); +	chip->timeout_b = 
>> msecs_to_jiffies(TIS_LONG_TIMEOUT); +	chip->timeout_c = 
>> msecs_to_jiffies(TIS_SHORT_TIMEOUT); +	chip->timeout_d = 
>> msecs_to_jiffies(TIS_SHORT_TIMEOUT); + + 
>> dev_set_drvdata(&chip->dev, priv); + 
>> init_completion(&priv->tpm_ready); + +	if (client->irq > 
>> 0) { +		rc = devm_request_irq(dev, client->irq, 
>> cr50_i2c_int_handler, + 
>> IRQF_TRIGGER_FALLING | IRQF_ONESHOT, + 
>> dev->driver->name, chip); +		if (rc < 0) { + 
>> dev_err(dev, "Failed to probe IRQ %d\n", client->irq); + 
>> return rc; +		} + +		disable_irq(client->irq); 
>> +		priv->irq = client->irq; +	} else { + 
>> dev_warn(dev, "No IRQ, will use %ums delay for TPM ready\n", + 
>> CR50_TIMEOUT_NOIRQ_MS); +	} + +	rc = 
>> request_locality(chip); +	if (rc < 0) { + 
>> dev_err(dev, "Could not request locality\n"); + 
>> return rc; +	} + +	/* Read four bytes from DID_VID register 
>> */ +	rc = cr50_i2c_read(chip, TPM_I2C_DID_VID(0), buf, 
>> sizeof(buf)); +	if (rc < 0) { +		dev_err(dev, 
>> "Could not read vendor id\n"); + 
>> cr50_release_locality(chip, CR50_FORCE); +		return rc; 
>> +	} + +	vendor = le32_to_cpup((__le32 *)buf); +	if (vendor 
>> != CR50_I2C_DID_VID) { +		dev_err(dev, "Vendor ID 
>> did not match! ID was %08x\n", vendor); + 
>> cr50_release_locality(chip, CR50_FORCE); +		return 
>> -ENODEV; +	} + +	dev_info(dev, "cr50 TPM 2.0 (i2c 0x%02x 
>> irq %d id 0x%x)\n", +		 client->addr, 
>> client->irq, vendor >> 16); + +	return 
>> tpm_chip_register(chip); +} + +/* + * cr50_i2c_probe - driver 
>> prbe function + * + * @client: i2x client information + * + * 
>> Returns 0 + */ +static int cr50_i2c_remove(struct i2c_client 
>> *client) +{ +	struct tpm_chip *chip = 
>> i2c_get_clientdata(client); + +	tpm_chip_unregister(chip); 
>> +	cr50_release_locality(chip, CR50_FORCE); + +	return 0; 
>> +} + +static SIMPLE_DEV_PM_OPS(cr50_i2c_pm, tpm_pm_suspend, 
>> tpm_pm_resume); + +static struct i2c_driver cr50_i2c_driver = { 
>> +	.id_table = cr50_i2c_table, +	.probe = cr50_i2c_probe, + 
>> .remove = cr50_i2c_remove, +	.driver = { +		.name = 
>> "cr50_i2c", +		.pm = &cr50_i2c_pm, + 
>> .acpi_match_table = ACPI_PTR(cr50_i2c_acpi_id), + 
>> .of_match_table = of_match_ptr(of_cr50_i2c_match), +	}, +}; + 
>> +module_i2c_driver(cr50_i2c_driver); + 
>> +MODULE_DESCRIPTION("cr50 TPM I2C Driver"); 
>> +MODULE_LICENSE("GPL"); --  2.29.2   
> 
> I did not enumerate every possible style error but instead 
> showed some examples, because there were so many.

Hi Jarkko,

I'll address the style issues in v3. Thank you for the feedback.

Adrian

>
> /Jarkko