Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753953AbcLGAQL (ORCPT ); Tue, 6 Dec 2016 19:16:11 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:35905 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753533AbcLGAP2 (ORCPT ); Tue, 6 Dec 2016 19:15:28 -0500 From: Chris Bostic To: robh+dt@kernel.org, mark.rutland@arm.com, linux@armlinux.org.uk, gregkh@linuxfoundation.org, sre@kernel.org, mturquette@baylibre.com, geert+renesas@glider.be, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Chris Bostic , joel@jms.id.au, jk@ozlabs.org, linux-kernel@vger.kernel.org, andrew@aj.id.au, alistair@popple.id.au, benh@kernel.crashing.org Subject: [PATCH 16/16] drivers/fsi: Add GPIO based FSI master Date: Tue, 6 Dec 2016 18:14:37 -0600 Message-Id: <1481069677-53660-17-git-send-email-christopher.lee.bostic@gmail.com> X-Mailer: git-send-email 2.7.4 (Apple Git-66) In-Reply-To: <1481069677-53660-1-git-send-email-christopher.lee.bostic@gmail.com> References: <1481069677-53660-1-git-send-email-christopher.lee.bostic@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16725 Lines: 604 From: Chris Bostic Implement a FSI master using GPIO. Will generate FSI protocol for read and write commands to particular addresses. Sends master command and waits for and decodes a slave response. Includes Jeremy Kerr's original GPIO master base commit. Signed-off-by: Jeremy Kerr Signed-off-by: Chris Bostic --- drivers/fsi/Kconfig | 7 + drivers/fsi/Makefile | 1 + drivers/fsi/fsi-master-gpio.c | 552 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 560 insertions(+) create mode 100644 drivers/fsi/fsi-master-gpio.c diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig index f065dbe..9530459 100644 --- a/drivers/fsi/Kconfig +++ b/drivers/fsi/Kconfig @@ -17,6 +17,13 @@ config FSI_MASTER_FAKE depends on FSI ---help--- This option enables a fake FSI master driver for debugging. + +config FSI_MASTER_GPIO + tristate "GPIO-based FSI master" + depends on FSI && GPIOLIB + ---help--- + This option enables a FSI master driver using GPIO lines. + endif endmenu diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile index 847c00c..2021ce5 100644 --- a/drivers/fsi/Makefile +++ b/drivers/fsi/Makefile @@ -1,3 +1,4 @@ obj-$(CONFIG_FSI) += fsi-core.o obj-$(CONFIG_FSI_MASTER_FAKE) += fsi-master-fake.o +obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c new file mode 100644 index 0000000..79cb0b1 --- /dev/null +++ b/drivers/fsi/fsi-master-gpio.c @@ -0,0 +1,552 @@ +/* + * A FSI master controller, using a simple GPIO bit-banging interface + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "fsi-master.h" + +#define FSI_GPIO_STD_DLY 1 /* Standard pin delay in nS */ +#define FSI_ECHO_DELAY_CLOCKS 16 /* Number clocks for echo delay */ +#define FSI_PRE_BREAK_CLOCKS 50 /* Number clocks to prep for break */ +#define FSI_BREAK_CLOCKS 256 /* Number of clocks to issue break */ +#define FSI_POST_BREAK_CLOCKS 16000 /* Number clocks to set up cfam */ +#define FSI_INIT_CLOCKS 5000 /* Clock out any old data */ +#define FSI_GPIO_STD_DELAY 10 /* Standard GPIO delay in nS */ + /* todo: adjust down as low as */ + /* possible or eliminate */ +#define FSI_GPIO_CMD_DPOLL 0x000000000000002AULL +#define FSI_GPIO_CMD_DPOLL_SIZE 9 +#define FSI_GPIO_DPOLL_CLOCKS 100 /* < 21 will cause slave to hang */ +#define FSI_GPIO_CMD_DEFAULT 0x2000000000000000ULL +#define FSI_GPIO_CMD_WRITE 0 +#define FSI_GPIO_CMD_READ 0x0400000000000000ULL +#define FSI_GPIO_CMD_SLAVE_MASK 0xC000000000000000ULL +#define FSI_GPIO_CMD_ADDR_SHIFT 37 +#define FSI_GPIO_CMD_ADDR_MASK 0x001FFFFF +#define FSI_GPIO_CMD_SLV_SHIFT 62 +#define FSI_GPIO_CMD_SIZE_16 0x0000001000000000ULL +#define FSI_GPIO_CMD_SIZE_32 0x0000003000000000ULL +#define FSI_GPIO_CMD_DT32_SHIFT 4 +#define FSI_GPIO_CMD_DT16_SHIFT 20 +#define FSI_GPIO_CMD_DT8_SHIFT 28 +#define FSI_GPIO_CMD_DFLT_LEN 28 +#define FSI_GPIO_CMD_CRC_SHIFT 60 + +/* Bus errors */ +#define FSI_GPIO_ERR_BUSY 1 /* Slave stuck in busy state */ +#define FSI_GPIO_RESP_ERRA 2 /* Any (misc) Error */ +#define FSI_GPIO_RESP_ERRC 3 /* Slave reports master CRC error */ +#define FSI_GPIO_MTOE 4 /* Master time out error */ +#define FSI_GPIO_CRC_INVAL 5 /* Master reports slave CRC error */ + +/* Normal slave responses */ +#define FSI_GPIO_RESP_BUSY 1 +#define FSI_GPIO_RESP_ACK 0 +#define FSI_GPIO_RESP_ACKD 4 + +#define FSI_GPIO_MAX_BUSY 100 +#define FSI_GPIO_MTOE_COUNT 1000 +#define FSI_GPIO_DRAIN_BITS 20 +#define FSI_GPIO_CRC_SIZE 4 +#define FSI_GPIO_MSG_ID_SIZE 2 +#define FSI_GPIO_MSG_RESPID_SIZE 2 +#define FSI_GPIO_PRIME_SLAVE_CLOCKS 100 + +static DEFINE_SPINLOCK(fsi_gpio_cmd_lock); /* lock around fsi commands */ + +struct fsi_master_gpio { + struct fsi_master master; + struct gpio_desc *gpio_clk; + struct gpio_desc *gpio_data; + struct gpio_desc *gpio_trans; /* Voltage translator */ + struct gpio_desc *gpio_enable; /* FSI enable */ + struct gpio_desc *gpio_mux; /* Mux control */ +}; + +#define to_fsi_master_gpio(m) container_of(m, struct fsi_master_gpio, master) + +struct fsi_gpio_msg { + uint64_t msg; + uint8_t bits; +}; + +static void clock_toggle(struct fsi_master_gpio *master, int count) +{ + int i; + + for (i = 0; i < count; i++) { + ndelay(FSI_GPIO_STD_DLY); + gpiod_set_value(master->gpio_clk, 0); + ndelay(FSI_GPIO_STD_DLY); + gpiod_set_value(master->gpio_clk, 1); + } +} + +static int sda_in(struct fsi_master_gpio *master) +{ + int in; + + ndelay(FSI_GPIO_STD_DLY); + in = gpiod_get_value(master->gpio_data); + return in ? 1 : 0; +} + +static void sda_out(struct fsi_master_gpio *master, int value) +{ + gpiod_set_value(master->gpio_data, value); +} + +static void set_sda_input(struct fsi_master_gpio *master) +{ + gpiod_direction_input(master->gpio_data); + if (master->gpio_trans) + gpiod_set_value(master->gpio_trans, 0); +} + +static void set_sda_output(struct fsi_master_gpio *master, int value) +{ + if (master->gpio_trans) + gpiod_set_value(master->gpio_trans, 1); + gpiod_direction_output(master->gpio_data, value); +} + +static void serial_in(struct fsi_master_gpio *master, struct fsi_gpio_msg *cmd, + uint8_t num_bits) +{ + uint8_t bit; + uint64_t msg = 0; + uint8_t in_bit = 0; + + set_sda_input(master); + + for (bit = 0; bit < num_bits; bit++) { + clock_toggle(master, 1); + in_bit = sda_in(master); + msg <<= 1; + msg |= ~in_bit & 0x1; /* Data is negative active */ + } + cmd->bits = num_bits; + cmd->msg = msg; +} + +static void serial_out(struct fsi_master_gpio *master, + const struct fsi_gpio_msg *cmd) +{ + uint8_t bit; + uint64_t msg = ~cmd->msg; /* Data is negative active */ + uint64_t sda_mask = 0x1ULL << (cmd->bits - 1); + uint64_t last_bit = ~0; + int next_bit; + + if (!cmd->bits) { + dev_warn(master->master.dev, "trying to output 0 bits\n"); + return; + } + set_sda_output(master, 0); + + /* Send the start bit */ + sda_out(master, 0); + clock_toggle(master, 1); + + /* Send the message */ + for (bit = 0; bit < cmd->bits; bit++) { + next_bit = (msg & sda_mask) >> (cmd->bits - 1); + if (last_bit ^ next_bit) { + sda_out(master, next_bit); + last_bit = next_bit; + } + clock_toggle(master, 1); + msg <<= 1; + } +} + +/* + * Clock out some 0's after every message to ride out line reflections + */ +static void echo_delay(struct fsi_master_gpio *master) +{ + set_sda_output(master, 1); + clock_toggle(master, FSI_ECHO_DELAY_CLOCKS); +} + +/* + * Used in bus error cases only. Clears out any remaining data the slave + * is attempting to send + */ +static void drain_response(struct fsi_master_gpio *master) +{ + struct fsi_gpio_msg msg; + + serial_in(master, &msg, FSI_GPIO_DRAIN_BITS); +} + +/* + * Store information on master errors so handler can detect and clean + * up the bus + */ +static void fsi_master_gpio_error(struct fsi_master_gpio *master, int error) +{ + +} + +static int poll_for_response(struct fsi_master_gpio *master, uint8_t expected, + uint8_t size, void *data) +{ + int busy_count = 0, i; + struct fsi_gpio_msg response, cmd; + int bits_remaining = 0, bit_count, response_id, id; + uint64_t resp = 0; + uint8_t bits_received = FSI_GPIO_MSG_ID_SIZE + + FSI_GPIO_MSG_RESPID_SIZE; + uint8_t crc_in; + + do { + for (i = 0; i < FSI_GPIO_MTOE_COUNT; i++) { + serial_in(master, &response, 1); + if (response.msg) + break; + } + if (i >= FSI_GPIO_MTOE_COUNT) { + dev_dbg(master->master.dev, + "Master time out waiting for response\n"); + drain_response(master); + fsi_master_gpio_error(master, FSI_GPIO_MTOE); + return -EIO; + } + + /* Response received */ + bit_count = FSI_GPIO_MSG_ID_SIZE + FSI_GPIO_MSG_RESPID_SIZE; + serial_in(master, &response, bit_count); + + response_id = response.msg & 0x3; + id = (response.msg >> FSI_GPIO_MSG_RESPID_SIZE) & 0x3; + dev_dbg(master->master.dev, "id:%d resp:%d\n", id, response_id); + + resp = response.msg; + + switch (response_id) { + case FSI_GPIO_RESP_ACK: + if (expected == FSI_GPIO_RESP_ACKD) + bits_remaining = 8 * size; + break; + + case FSI_GPIO_RESP_BUSY: + /* + * Its necessary to clock slave before issuing + * d-poll, not indicated in the hardware protocol + * spec. < 20 clocks causes slave to hang, 21 ok. + */ + set_sda_output(master, 1); + clock_toggle(master, FSI_GPIO_DPOLL_CLOCKS); + cmd.msg = FSI_GPIO_CMD_DPOLL; + cmd.bits = FSI_GPIO_CMD_DPOLL_SIZE; + serial_out(master, &cmd); + echo_delay(master); + continue; + + case FSI_GPIO_RESP_ERRA: + case FSI_GPIO_RESP_ERRC: + dev_dbg(master->master.dev, "ERR received: %d\n", + (int)response.msg); + /* + * todo: Verify crc from slave and in general + * only act on any response if crc is correct + */ + clock_toggle(master, FSI_GPIO_CRC_SIZE); + fsi_master_gpio_error(master, response.msg); + return -EIO; + } + + /* Read in the data field if applicable */ + if (bits_remaining) { + serial_in(master, &response, bits_remaining); + resp <<= bits_remaining; + resp |= response.msg; + bits_received += bits_remaining; + *((uint32_t *)data) = response.msg; + } + + crc_in = fsi_crc4(0, resp | (0x1ULL << bits_received), + bits_received + 1); + + /* Read in the crc and check it */ + serial_in(master, &response, FSI_GPIO_CRC_SIZE); + if (crc_in != response.msg) { + dev_dbg(master->master.dev, "ERR response CRC\n"); + fsi_master_gpio_error(master, FSI_GPIO_CRC_INVAL); + return -EIO; + } + /* Clock the slave enough to be ready for next operation */ + clock_toggle(master, FSI_GPIO_PRIME_SLAVE_CLOCKS); + return 0; + + } while (busy_count++ < FSI_GPIO_MAX_BUSY); + + dev_dbg(master->master.dev, "ERR slave is stuck in busy state\n"); + fsi_master_gpio_error(master, FSI_GPIO_ERR_BUSY); + + return -EIO; +} + +static void build_abs_ar_command(struct fsi_gpio_msg *cmd, uint64_t mode, + uint8_t slave, uint32_t addr, size_t size, + const void *data) +{ + uint8_t crc; + + cmd->bits = FSI_GPIO_CMD_DFLT_LEN; + cmd->msg = FSI_GPIO_CMD_DEFAULT; + cmd->msg |= mode; + cmd->msg &= ~FSI_GPIO_CMD_SLAVE_MASK; + cmd->msg |= (((uint64_t)slave) << FSI_GPIO_CMD_SLV_SHIFT); + addr &= FSI_GPIO_CMD_ADDR_MASK; + cmd->msg |= (((uint64_t)addr) << FSI_GPIO_CMD_ADDR_SHIFT); + if (size == sizeof(uint8_t)) { + if (data) { + uint8_t cmd_data = *((uint8_t *)data); + + cmd->msg |= + ((uint64_t)cmd_data) << FSI_GPIO_CMD_DT8_SHIFT; + } + } else if (size == sizeof(uint16_t)) { + cmd->msg |= FSI_GPIO_CMD_SIZE_16; + if (data) { + uint16_t cmd_data; + + memcpy(&cmd_data, data, size); + cmd->msg |= + ((uint64_t)cmd_data) << FSI_GPIO_CMD_DT16_SHIFT; + } + } else { + cmd->msg |= FSI_GPIO_CMD_SIZE_32; + if (data) { + uint32_t cmd_data; + + memcpy(&cmd_data, data, size); + cmd->msg |= + ((uint64_t)cmd_data) << FSI_GPIO_CMD_DT32_SHIFT; + } + } + + if (mode == FSI_GPIO_CMD_WRITE) + cmd->bits += (8 * size); + + /* Include start bit */ + crc = fsi_crc4(0, + (cmd->msg >> (64 - cmd->bits)) | (0x1ULL << cmd->bits), + cmd->bits + 1); + cmd->msg |= ((uint64_t)crc) << (FSI_GPIO_CMD_CRC_SHIFT - cmd->bits); + cmd->bits += FSI_GPIO_CRC_SIZE; + + /* Right align message */ + cmd->msg >>= (64 - cmd->bits); +} + +static int fsi_master_gpio_read(struct fsi_master *_master, int link, + uint8_t slave, uint32_t addr, void *val, size_t size) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + struct fsi_gpio_msg cmd; + int rc; + unsigned long flags; + + if (link != 0) + return -ENODEV; + + build_abs_ar_command(&cmd, FSI_GPIO_CMD_READ, slave, addr, size, NULL); + + spin_lock_irqsave(&fsi_gpio_cmd_lock, flags); + serial_out(master, &cmd); + echo_delay(master); + rc = poll_for_response(master, FSI_GPIO_RESP_ACKD, size, val); + spin_unlock_irqrestore(&fsi_gpio_cmd_lock, flags); + + return rc; +} + +static int fsi_master_gpio_write(struct fsi_master *_master, int link, + uint8_t slave, uint32_t addr, const void *val, size_t size) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + struct fsi_gpio_msg cmd; + int rc; + unsigned long flags; + + if (link != 0) + return -ENODEV; + + build_abs_ar_command(&cmd, FSI_GPIO_CMD_WRITE, slave, addr, size, val); + + spin_lock_irqsave(&fsi_gpio_cmd_lock, flags); + serial_out(master, &cmd); + echo_delay(master); + rc = poll_for_response(master, FSI_GPIO_RESP_ACK, size, NULL); + spin_unlock_irqrestore(&fsi_gpio_cmd_lock, flags); + + return rc; +} + +/* + * Issue a break command on link + */ +static int fsi_master_gpio_break(struct fsi_master *_master, int link) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + + if (link != 0) + return -ENODEV; + + set_sda_output(master, 1); + clock_toggle(master, FSI_PRE_BREAK_CLOCKS); + sda_out(master, 0); + clock_toggle(master, FSI_BREAK_CLOCKS); + echo_delay(master); + sda_out(master, 1); + clock_toggle(master, FSI_POST_BREAK_CLOCKS); + + /* Wait for logic reset to take effect */ + udelay(200); + + return 0; +} + +static void fsi_master_gpio_init(struct fsi_master_gpio *master) +{ + if (master->gpio_mux) + gpiod_direction_output(master->gpio_mux, 1); + if (master->gpio_trans) + gpiod_direction_output(master->gpio_trans, 1); + if (master->gpio_enable) + gpiod_direction_output(master->gpio_enable, 1); + gpiod_direction_output(master->gpio_clk, 1); + gpiod_direction_output(master->gpio_data, 1); + + /* todo: evaluate if clocks can be reduced */ + clock_toggle(master, FSI_INIT_CLOCKS); +} + +static int fsi_master_gpio_link_enable(struct fsi_master *_master, int link) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + + if (link != 0) + return -ENODEV; + if (master->gpio_enable) + gpiod_set_value(master->gpio_enable, 1); + + return 0; +} + +static ssize_t store_scan(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t count) +{ + struct fsi_master_gpio *master = dev_get_drvdata(dev); + + fsi_master_gpio_init(master); + + /* clear out any old scan data if present */ + fsi_master_unregister(&master->master); + fsi_master_register(&master->master); + + return count; +} + +static DEVICE_ATTR(scan, 0200, NULL, store_scan); + +static int fsi_master_gpio_probe(struct platform_device *pdev) +{ + struct fsi_master_gpio *master; + struct gpio_desc *gpio; + + master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL); + if (!master) + return -ENOMEM; + + gpio = devm_gpiod_get(&pdev->dev, "clock", 0); + if (IS_ERR(gpio)) { + dev_dbg(&pdev->dev, "probe: failed to get clock pin\n"); + return PTR_ERR(gpio); + } + master->gpio_clk = gpio; + + gpio = devm_gpiod_get(&pdev->dev, "data", 0); + if (IS_ERR(gpio)) { + dev_dbg(&pdev->dev, "probe: failed to get data pin\n"); + return PTR_ERR(gpio); + } + master->gpio_data = gpio; + + /* Optional pins */ + + gpio = devm_gpiod_get(&pdev->dev, "trans", 0); + if (IS_ERR(gpio)) + dev_dbg(&pdev->dev, "probe: failed to get trans pin\n"); + else + master->gpio_trans = gpio; + + gpio = devm_gpiod_get(&pdev->dev, "enable", 0); + if (IS_ERR(gpio)) + dev_dbg(&pdev->dev, "probe: failed to get enable pin\n"); + else + master->gpio_enable = gpio; + + gpio = devm_gpiod_get(&pdev->dev, "mux", 0); + if (IS_ERR(gpio)) + dev_dbg(&pdev->dev, "probe: failed to get mux pin\n"); + else + master->gpio_mux = gpio; + + master->master.n_links = 1; + master->master.read = fsi_master_gpio_read; + master->master.write = fsi_master_gpio_write; + master->master.send_break = fsi_master_gpio_break; + master->master.link_enable = fsi_master_gpio_link_enable; + platform_set_drvdata(pdev, master); + + return device_create_file(&pdev->dev, &dev_attr_scan); +} + + +static int fsi_master_gpio_remove(struct platform_device *pdev) +{ + struct fsi_master_gpio *master = platform_get_drvdata(pdev); + + devm_gpiod_put(&pdev->dev, master->gpio_clk); + devm_gpiod_put(&pdev->dev, master->gpio_data); + if (master->gpio_trans) + devm_gpiod_put(&pdev->dev, master->gpio_trans); + if (master->gpio_enable) + devm_gpiod_put(&pdev->dev, master->gpio_enable); + if (master->gpio_mux) + devm_gpiod_put(&pdev->dev, master->gpio_mux); + fsi_master_unregister(&master->master); + + return 0; +} + +static const struct of_device_id fsi_master_gpio_match[] = { + { .compatible = "ibm,fsi-master-gpio" }, + { }, +}; + +static struct platform_driver fsi_master_gpio_driver = { + .driver = { + .name = "fsi-master-gpio", + .of_match_table = fsi_master_gpio_match, + }, + .probe = fsi_master_gpio_probe, + .remove = fsi_master_gpio_remove, +}; + +module_platform_driver(fsi_master_gpio_driver); +MODULE_LICENSE("GPL"); -- 1.8.2.2