diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-driver-fsi-master-gpio | 10 | ||||
| -rw-r--r-- | drivers/fsi/fsi-master-gpio.c | 78 |
2 files changed, 86 insertions, 2 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-fsi-master-gpio b/Documentation/ABI/testing/sysfs-driver-fsi-master-gpio new file mode 100644 index 000000000000..1f29c8843cfd --- /dev/null +++ b/Documentation/ABI/testing/sysfs-driver-fsi-master-gpio @@ -0,0 +1,10 @@ +What: /sys/bus/platform/devices/[..]/fsi-master-gpio/external_mode +Date: Feb 2018 +KernelVersion: 4.17 +Contact: jk@ozlabs.org +Description: + Controls access arbitration for GPIO-based FSI master. A + value of 0 (the default) sets normal mode, where the + driver performs FSI bus transactions, 1 sets external mode, + where the FSI bus is driven externally (for example, by + a debug device). diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c index a6d602e89c11..b54c213f3dcb 100644 --- a/drivers/fsi/fsi-master-gpio.c +++ b/drivers/fsi/fsi-master-gpio.c @@ -59,6 +59,7 @@ struct fsi_master_gpio { struct gpio_desc *gpio_trans; /* Voltage translator */ struct gpio_desc *gpio_enable; /* FSI enable */ struct gpio_desc *gpio_mux; /* Mux control */ + bool external_mode; }; #define CREATE_TRACE_POINTS @@ -411,6 +412,12 @@ static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave, int rc; spin_lock_irqsave(&master->cmd_lock, flags); + + if (master->external_mode) { + spin_unlock_irqrestore(&master->cmd_lock, flags); + return -EBUSY; + } + serial_out(master, cmd); echo_delay(master); rc = poll_for_response(master, slave, resp_len, resp); @@ -469,6 +476,10 @@ static int fsi_master_gpio_break(struct fsi_master *_master, int link) trace_fsi_master_gpio_break(master); spin_lock_irqsave(&master->cmd_lock, flags); + if (master->external_mode) { + spin_unlock_irqrestore(&master->cmd_lock, flags); + return -EBUSY; + } set_sda_output(master, 1); sda_out(master, 1); clock_toggle(master, FSI_PRE_BREAK_CLOCKS); @@ -497,25 +508,84 @@ static void fsi_master_gpio_init(struct fsi_master_gpio *master) clock_zeros(master, FSI_INIT_CLOCKS); } +static void fsi_master_gpio_init_external(struct fsi_master_gpio *master) +{ + gpiod_direction_output(master->gpio_mux, 0); + gpiod_direction_output(master->gpio_trans, 0); + gpiod_direction_output(master->gpio_enable, 1); + gpiod_direction_input(master->gpio_clk); + gpiod_direction_input(master->gpio_data); +} + static int fsi_master_gpio_link_enable(struct fsi_master *_master, int link) { struct fsi_master_gpio *master = to_fsi_master_gpio(_master); unsigned long flags; + int rc = -EBUSY; if (link != 0) return -ENODEV; spin_lock_irqsave(&master->cmd_lock, flags); - gpiod_set_value(master->gpio_enable, 1); + if (!master->external_mode) { + gpiod_set_value(master->gpio_enable, 1); + rc = 0; + } spin_unlock_irqrestore(&master->cmd_lock, flags); - return 0; + return rc; +} + +static ssize_t external_mode_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct fsi_master_gpio *master = dev_get_drvdata(dev); + + return snprintf(buf, PAGE_SIZE - 1, "%u\n", + master->external_mode ? 1 : 0); +} + +static ssize_t external_mode_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + struct fsi_master_gpio *master = dev_get_drvdata(dev); + unsigned long flags, val; + bool external_mode; + int err; + + err = kstrtoul(buf, 0, &val); + if (err) + return err; + + external_mode = !!val; + + spin_lock_irqsave(&master->cmd_lock, flags); + + if (external_mode == master->external_mode) { + spin_unlock_irqrestore(&master->cmd_lock, flags); + return count; + } + + master->external_mode = external_mode; + if (master->external_mode) + fsi_master_gpio_init_external(master); + else + fsi_master_gpio_init(master); + spin_unlock_irqrestore(&master->cmd_lock, flags); + + fsi_master_rescan(&master->master); + + return count; } +static DEVICE_ATTR(external_mode, 0664, + external_mode_show, external_mode_store); + static int fsi_master_gpio_probe(struct platform_device *pdev) { struct fsi_master_gpio *master; struct gpio_desc *gpio; + int rc; master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL); if (!master) @@ -572,6 +642,10 @@ static int fsi_master_gpio_probe(struct platform_device *pdev) fsi_master_gpio_init(master); + rc = device_create_file(&pdev->dev, &dev_attr_external_mode); + if (rc) + return rc; + return fsi_master_register(&master->master); } |