Serial modules (I-870xxW series) implement DCON protocol which allows one-master-many-slaves configuration over RS-485. When these modules are installed into the device, they could be accessed using the 2nd PXA built-in UART port (/dev/ttySA1). However, it seems that addresses are not processed by the modules. So the parallel bus needs to select which slot is connected.
Signed-off-by: Sergei Ianovich <[email protected]> --- v0..v2 * use device tree * use devm helpers where possible .../devicetree/bindings/misc/lp8x4x-bus.txt | 8 ++- Documentation/misc-devices/lp8x4x_bus.txt | 15 ++++- drivers/misc/lp8x4x_bus.c | 75 ++++++++++++++++++++-- 3 files changed, 87 insertions(+), 11 deletions(-) diff --git a/Documentation/devicetree/bindings/misc/lp8x4x-bus.txt b/Documentation/devicetree/bindings/misc/lp8x4x-bus.txt index 1c87a29..61ac96e 100644 --- a/Documentation/devicetree/bindings/misc/lp8x4x-bus.txt +++ b/Documentation/devicetree/bindings/misc/lp8x4x-bus.txt @@ -5,12 +5,14 @@ See Documentation/misc-devices/lp8x4x_bus.txt for details. Required properties: - compatible : should be "icpdas,backplane-lp8x4x" -- reg: physical base address of the slot count register and the length - of the memory mapped region. +- reg: physical base addresses and region lengths of + * the slot count register + * the serial slot select register Example: backplane { compatible = "icpdas,backplane-lp8x4x"; - reg = <0x17009046 0x2>; + reg = <0x17009046 0x2 + 0x17009004 0x2>; }; diff --git a/Documentation/misc-devices/lp8x4x_bus.txt b/Documentation/misc-devices/lp8x4x_bus.txt index f5392b3..d9a069d 100644 --- a/Documentation/misc-devices/lp8x4x_bus.txt +++ b/Documentation/misc-devices/lp8x4x_bus.txt @@ -19,7 +19,14 @@ LP-8x4x is an ARM-based industrial computer with a custom parallel bus to connect expansion modules with digital input/output, analog input/output, serial, CAN and other types of ports. -The bus is implemented by a FPGA. +The bus is implemented by a FPGA. There are two major groups of expansion +modules: serial and parallel. + +Serial modules (I-870xxW series) implement DCON protocol which allows one- +master-many-slaves configuration over RS-485. When these modules are installed +into the device, they could be accessed using the 2nd PXA built-in UART port +(/dev/ttyS1). However, it seems that addresses are not processed by +the modules. So the parallel bus needs to select which slot is connected. SYSFS ----- @@ -28,3 +35,9 @@ SYSFS slot_count RO - shows total number of expansion slots on the device + +active_slot + RW - connects the select slot for serial communications. If there + is a parallel module in the selected slot, it simply ignores + incoming packets. So it is safe to activate any available + slot. diff --git a/drivers/misc/lp8x4x_bus.c b/drivers/misc/lp8x4x_bus.c index 7119738..cffe121 100644 --- a/drivers/misc/lp8x4x_bus.c +++ b/drivers/misc/lp8x4x_bus.c @@ -24,6 +24,8 @@ MODULE_DESCRIPTION("ICP DAS LP-8x4x parallel bus driver"); struct lp8x4x_master { unsigned int slot_count; void *count_addr; + unsigned int active_slot; + void *switch_addr; struct device dev; }; @@ -55,8 +57,45 @@ static ssize_t slot_count_show(struct device *dev, static DEVICE_ATTR_RO(slot_count); +static ssize_t active_slot_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct lp8x4x_master *m = container_of(dev, struct lp8x4x_master, dev); + + return sprintf(buf, "%u\n", m->active_slot); +} + +static ssize_t active_slot_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + struct lp8x4x_master *m = container_of(dev, struct lp8x4x_master, dev); + unsigned int active_slot = 0; + int err; + + if (!buf) + return count; + if (0 == count) + return count; + + err = kstrtouint(buf, 10, &active_slot); + if (err != 0 || !active_slot || active_slot > m->slot_count) { + dev_err(dev, "slot number is out of range 1..%u\n", + m->slot_count); + return count; + } + + m->active_slot = active_slot; + + iowrite8((1 << (m->active_slot - 1)) ^ 0xff, m->switch_addr); + + return count; +} + +static DEVICE_ATTR_RW(active_slot); + static struct attribute *master_dev_attrs[] = { &dev_attr_slot_count.attr, + &dev_attr_active_slot.attr, NULL, }; ATTRIBUTE_GROUPS(master_dev); @@ -69,6 +108,9 @@ static void devm_lp8x4x_bus_release(struct device *dev, void *res) dev_dbg(dev, "releasing devices\n"); device_unregister(&m->dev); bus_unregister(&lp8x4x_bus_type); + + /* Disable serial communications */ + iowrite8(0xff, m->switch_addr); } static int __init lp8x4x_bus_probe(struct platform_device *pdev) @@ -90,8 +132,9 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev) res = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!res) { + dev_err(&pdev->dev, "Failed to get slot number address\n"); err = -ENODEV; - goto err2; + goto err_free; } m->count_addr = devm_ioremap_resource(&pdev->dev, res); @@ -99,7 +142,22 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev) dev_err(&pdev->dev, "Failed to ioremap %p\n", m->count_addr); err = -EFAULT; - goto err2; + goto err_free; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 1); + if (!res) { + dev_err(&pdev->dev, "Failed to get slot switch address\n"); + err = -ENODEV; + goto err_free; + } + + m->switch_addr = devm_ioremap_resource(&pdev->dev, res); + if (!m->switch_addr) { + dev_err(&pdev->dev, "Failed to ioremap %p\n", + m->switch_addr); + err = -EFAULT; + goto err_free; } m->slot_count = ioread8(m->count_addr); @@ -113,15 +171,18 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev) default: dev_err(&pdev->dev, "unexpected slot number(%u)", m->slot_count); - goto err2; + goto err_free; }; dev_info(&pdev->dev, "found bus with up to %u slots\n", m->slot_count); + /* Disable serial communications until explicitly enabled */ + iowrite8(0xff, m->switch_addr); + err = bus_register(&lp8x4x_bus_type); if (err < 0) { dev_err(&pdev->dev, "failed to register bus type\n"); - goto err3; + goto err_free; } m->dev.bus = &lp8x4x_bus_type; @@ -133,15 +194,15 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev) err = device_register(&m->dev); if (err < 0) { dev_err(&pdev->dev, "failed to register backplane device\n"); - goto err3; + goto err_bus; } devres_add(&pdev->dev, p); return 0; -err3: +err_bus: bus_unregister(&lp8x4x_bus_type); -err2: +err_free: devres_free(p); err1: kfree(m); -- 1.8.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
