diff options
Diffstat (limited to 'drivers/fsi/fsi-master-gpio.c')
| -rw-r--r-- | drivers/fsi/fsi-master-gpio.c | 604 |
1 files changed, 604 insertions, 0 deletions
diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c new file mode 100644 index 000000000000..ae2618768508 --- /dev/null +++ b/drivers/fsi/fsi-master-gpio.c @@ -0,0 +1,604 @@ +/* + * A FSI master controller, using a simple GPIO bit-banging interface + */ + +#include <linux/crc4.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/fsi.h> +#include <linux/gpio/consumer.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#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 0x2 +#define FSI_GPIO_CMD_TERM 0x3f +#define FSI_GPIO_CMD_ABS_AR 0x4 + +#define FSI_GPIO_DPOLL_CLOCKS 100 /* < 21 will cause slave to hang */ + +/* 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 + +struct fsi_master_gpio { + struct fsi_master master; + struct device *dev; + spinlock_t cmd_lock; /* Lock for commands */ + 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 CREATE_TRACE_POINTS +#include <trace/events/fsi_master_gpio.h> + +#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); + gpiod_set_value(master->gpio_trans, 0); +} + +static void set_sda_output(struct fsi_master_gpio *master, int value) +{ + gpiod_set_value(master->gpio_trans, 1); + gpiod_direction_output(master->gpio_data, value); +} + +static void clock_zeros(struct fsi_master_gpio *master, int count) +{ + set_sda_output(master, 1); + clock_toggle(master, count); +} + +static void serial_in(struct fsi_master_gpio *master, struct fsi_gpio_msg *msg, + uint8_t num_bits) +{ + uint8_t bit, in_bit; + + set_sda_input(master); + + for (bit = 0; bit < num_bits; bit++) { + clock_toggle(master, 1); + in_bit = sda_in(master); + msg->msg <<= 1; + msg->msg |= ~in_bit & 0x1; /* Data is active low */ + } + msg->bits += num_bits; + + trace_fsi_master_gpio_in(master, num_bits, 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 active low */ + uint64_t sda_mask = 0x1ULL << (cmd->bits - 1); + uint64_t last_bit = ~0; + int next_bit; + + trace_fsi_master_gpio_out(master, cmd->bits, cmd->msg); + + if (!cmd->bits) { + dev_warn(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; + } +} + +static void msg_push_bits(struct fsi_gpio_msg *msg, uint64_t data, int bits) +{ + msg->msg <<= bits; + msg->msg |= data & ((1ull << bits) - 1); + msg->bits += bits; +} + +static void msg_push_crc(struct fsi_gpio_msg *msg) +{ + uint8_t crc; + int top; + + top = msg->bits & 0x3; + + /* start bit, and any non-aligned top bits */ + crc = crc4(0, 1 << top | msg->msg >> (msg->bits - top), top + 1); + + /* aligned bits */ + crc = crc4(crc, msg->msg, msg->bits - top); + + msg_push_bits(msg, crc, 4); +} + +/* + * Encode an Absolute Address command + */ +static void build_abs_ar_command(struct fsi_gpio_msg *cmd, + uint8_t id, uint32_t addr, size_t size, const void *data) +{ + bool write = !!data; + uint8_t ds; + int i; + + cmd->bits = 0; + cmd->msg = 0; + + msg_push_bits(cmd, id, 2); + msg_push_bits(cmd, FSI_GPIO_CMD_ABS_AR, 3); + msg_push_bits(cmd, write ? 0 : 1, 1); + + /* + * The read/write size is encoded in the lower bits of the address + * (as it must be naturally-aligned), and the following ds bit. + * + * size addr:1 addr:0 ds + * 1 x x 0 + * 2 x 0 1 + * 4 0 1 1 + * + */ + ds = size > 1 ? 1 : 0; + addr &= ~(size - 1); + if (size == 4) + addr |= 1; + + msg_push_bits(cmd, addr & ((1 << 21) - 1), 21); + msg_push_bits(cmd, ds, 1); + for (i = 0; write && i < size; i++) + msg_push_bits(cmd, ((uint8_t *)data)[i], 8); + + msg_push_crc(cmd); +} + +static void build_dpoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id) +{ + cmd->bits = 0; + cmd->msg = 0; + + msg_push_bits(cmd, slave_id, 2); + msg_push_bits(cmd, FSI_GPIO_CMD_DPOLL, 3); + msg_push_crc(cmd); +} + +static void echo_delay(struct fsi_master_gpio *master) +{ + set_sda_output(master, 1); + clock_toggle(master, FSI_ECHO_DELAY_CLOCKS); +} + +static void build_term_command(struct fsi_gpio_msg *cmd, uint8_t slave_id) +{ + cmd->bits = 0; + cmd->msg = 0; + + msg_push_bits(cmd, slave_id, 2); + msg_push_bits(cmd, FSI_GPIO_CMD_TERM, 6); + msg_push_crc(cmd); +} + +/* + * 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 read_one_response(struct fsi_master_gpio *master, + uint8_t data_size, struct fsi_gpio_msg *msgp, uint8_t *tagp) +{ + struct fsi_gpio_msg msg; + uint8_t id, tag; + uint32_t crc; + int i; + + /* wait for the start bit */ + for (i = 0; i < FSI_GPIO_MTOE_COUNT; i++) { + msg.bits = 0; + msg.msg = 0; + serial_in(master, &msg, 1); + if (msg.msg) + break; + } + if (i == FSI_GPIO_MTOE_COUNT) { + dev_dbg(master->dev, + "Master time out waiting for response\n"); + fsi_master_gpio_error(master, FSI_GPIO_MTOE); + return -EIO; + } + + msg.bits = 0; + msg.msg = 0; + + /* Read slave ID & response tag */ + serial_in(master, &msg, 4); + + id = (msg.msg >> FSI_GPIO_MSG_RESPID_SIZE) & 0x3; + tag = msg.msg & 0x3; + + /* If we have an ACK and we're expecting data, clock the data in too */ + if (tag == FSI_GPIO_RESP_ACK && data_size) + serial_in(master, &msg, data_size * 8); + + /* read CRC */ + serial_in(master, &msg, FSI_GPIO_CRC_SIZE); + + /* we have a whole message now; check CRC */ + crc = crc4(0, 1, 1); + crc = crc4(crc, msg.msg, msg.bits); + if (crc) { + dev_dbg(master->dev, "ERR response CRC\n"); + fsi_master_gpio_error(master, FSI_GPIO_CRC_INVAL); + return -EIO; + } + + if (msgp) + *msgp = msg; + if (tagp) + *tagp = tag; + + return 0; +} + +static int issue_term(struct fsi_master_gpio *master, uint8_t slave) +{ + struct fsi_gpio_msg cmd; + uint8_t tag; + int rc; + + build_term_command(&cmd, slave); + serial_out(master, &cmd); + echo_delay(master); + + rc = read_one_response(master, 0, NULL, &tag); + if (rc < 0) { + dev_err(master->dev, + "TERM failed; lost communication with slave\n"); + return -EIO; + } else if (tag != FSI_GPIO_RESP_ACK) { + dev_err(master->dev, "TERM failed; response %d\n", tag); + return -EIO; + } + + return 0; +} + +static int poll_for_response(struct fsi_master_gpio *master, + uint8_t slave, uint8_t size, void *data) +{ + struct fsi_gpio_msg response, cmd; + int busy_count = 0, rc, i; + uint8_t tag; + uint8_t *data_byte = data; + +retry: + rc = read_one_response(master, size, &response, &tag); + if (rc) + return rc; + + switch (tag) { + case FSI_GPIO_RESP_ACK: + if (size && data) { + uint64_t val = response.msg; + /* clear crc & mask */ + val >>= 4; + val &= (1ull << (size * 8)) - 1; + + for (i = 0; i < size; i++) { + data_byte[size-i-1] = val; + val >>= 8; + } + } + 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. + */ + clock_zeros(master, FSI_GPIO_DPOLL_CLOCKS); + if (busy_count++ < FSI_GPIO_MAX_BUSY) { + build_dpoll_command(&cmd, slave); + serial_out(master, &cmd); + echo_delay(master); + goto retry; + } + dev_warn(master->dev, + "ERR slave is stuck in busy state, issuing TERM\n"); + issue_term(master, slave); + rc = -EIO; + break; + + case FSI_GPIO_RESP_ERRA: + case FSI_GPIO_RESP_ERRC: + dev_dbg(master->dev, "ERR%c received: 0x%x\n", + tag == FSI_GPIO_RESP_ERRA ? 'A' : 'C', + (int)response.msg); + fsi_master_gpio_error(master, response.msg); + rc = -EIO; + break; + } + + /* Clock the slave enough to be ready for next operation */ + clock_zeros(master, FSI_GPIO_PRIME_SLAVE_CLOCKS); + return rc; +} + +static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave, + struct fsi_gpio_msg *cmd, size_t resp_len, void *resp) +{ + unsigned long flags; + int rc; + + spin_lock_irqsave(&master->cmd_lock, flags); + serial_out(master, cmd); + echo_delay(master); + rc = poll_for_response(master, slave, resp_len, resp); + spin_unlock_irqrestore(&master->cmd_lock, flags); + + return rc; +} + +static int fsi_master_gpio_read(struct fsi_master *_master, int link, + uint8_t id, uint32_t addr, void *val, size_t size) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + struct fsi_gpio_msg cmd; + + if (link != 0) + return -ENODEV; + + build_abs_ar_command(&cmd, id, addr, size, NULL); + return fsi_master_gpio_xfer(master, id, &cmd, size, val); +} + +static int fsi_master_gpio_write(struct fsi_master *_master, int link, + uint8_t id, uint32_t addr, const void *val, size_t size) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + struct fsi_gpio_msg cmd; + + if (link != 0) + return -ENODEV; + + build_abs_ar_command(&cmd, id, addr, size, val); + return fsi_master_gpio_xfer(master, id, &cmd, 0, NULL); +} + +static int fsi_master_gpio_term(struct fsi_master *_master, + int link, uint8_t id) +{ + struct fsi_master_gpio *master = to_fsi_master_gpio(_master); + struct fsi_gpio_msg cmd; + + if (link != 0) + return -ENODEV; + + build_term_command(&cmd, id); + return fsi_master_gpio_xfer(master, id, &cmd, 0, NULL); +} + +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; + + trace_fsi_master_gpio_break(master); + + set_sda_output(master, 1); + sda_out(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) +{ + gpiod_direction_output(master->gpio_mux, 1); + gpiod_direction_output(master->gpio_trans, 1); + 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_zeros(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; + gpiod_set_value(master->gpio_enable, 1); + + return 0; +} + +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; + + master->dev = &pdev->dev; + master->master.dev.parent = master->dev; + + gpio = devm_gpiod_get(&pdev->dev, "clock", 0); + if (IS_ERR(gpio)) { + dev_err(&pdev->dev, "failed to get clock gpio\n"); + return PTR_ERR(gpio); + } + master->gpio_clk = gpio; + + gpio = devm_gpiod_get(&pdev->dev, "data", 0); + if (IS_ERR(gpio)) { + dev_err(&pdev->dev, "failed to get data gpio\n"); + return PTR_ERR(gpio); + } + master->gpio_data = gpio; + + /* Optional GPIOs */ + gpio = devm_gpiod_get_optional(&pdev->dev, "trans", 0); + if (IS_ERR(gpio)) { + dev_err(&pdev->dev, "failed to get trans gpio\n"); + return PTR_ERR(gpio); + } + master->gpio_trans = gpio; + + gpio = devm_gpiod_get_optional(&pdev->dev, "enable", 0); + if (IS_ERR(gpio)) { + dev_err(&pdev->dev, "failed to get enable gpio\n"); + return PTR_ERR(gpio); + } + master->gpio_enable = gpio; + + gpio = devm_gpiod_get_optional(&pdev->dev, "mux", 0); + if (IS_ERR(gpio)) { + dev_err(&pdev->dev, "failed to get mux gpio\n"); + return PTR_ERR(gpio); + } + master->gpio_mux = gpio; + + master->master.n_links = 1; + master->master.flags = FSI_MASTER_FLAG_SWCLOCK; + master->master.read = fsi_master_gpio_read; + master->master.write = fsi_master_gpio_write; + master->master.term = fsi_master_gpio_term; + master->master.send_break = fsi_master_gpio_break; + master->master.link_enable = fsi_master_gpio_link_enable; + platform_set_drvdata(pdev, master); + spin_lock_init(&master->cmd_lock); + + fsi_master_gpio_init(master); + + return fsi_master_register(&master->master); +} + + +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 = "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"); |