--- /dev/null
+Qualcomm External Bus Interface 2 (EBI2)
+
+The EBI2 contains two peripheral blocks: XMEM and LCDC. The XMEM handles any
+external memory (such as NAND or other memory-mapped peripherals) whereas
+LCDC handles LCD displays.
+
+As it says it connects devices to an external bus interface, meaning address
+lines (up to 9 address lines so can only address 1KiB external memory space),
+data lines (16 bits), OE (output enable), ADV (address valid, used on some
+NOR flash memories), WE (write enable). This on top of 6 different chip selects
+(CS0 thru CS5) so that in theory 6 different devices can be connected.
+
+Apparently this bus is clocked at 64MHz. It has dedicated pins on the package
+and the bus can only come out on these pins, however if some of the pins are
+unused they can be left unconnected or remuxed to be used as GPIO or in some
+cases other orthogonal functions as well.
+
+Also CS1 and CS2 has -A and -B signals. Why they have that is unclear to me.
+
+The chip selects have the following memory range assignments. This region of
+memory is referred to as "Chip Peripheral SS FPB0" and is 168MB big.
+
+Chip Select Physical address base
+CS0 GPIO134 0x1a800000-0x1b000000 (8MB)
+CS1 GPIO39 (A) / GPIO123 (B) 0x1b000000-0x1b800000 (8MB)
+CS2 GPIO40 (A) / GPIO124 (B) 0x1b800000-0x1c000000 (8MB)
+CS3 GPIO133 0x1d000000-0x25000000 (128 MB)
+CS4 GPIO132 0x1c800000-0x1d000000 (8MB)
+CS5 GPIO131 0x1c000000-0x1c800000 (8MB)
+
+The APQ8060 Qualcomm Application Processor User Guide, 80-N7150-14 Rev. A,
+August 6, 2012 contains some incomplete documentation of the EBI2.
+
+FIXME: the manual mentions "write precharge cycles" and "precharge cycles".
+We have not been able to figure out which bit fields these correspond to
+in the hardware, or what valid values exist. The current hypothesis is that
+this is something just used on the FAST chip selects and that the SLOW
+chip selects are understood fully. There is also a "byte device enable"
+flag somewhere for 8bit memories.
+
+FIXME: The chipselects have SLOW and FAST configuration registers. It's a bit
+unclear what this means, if they are mutually exclusive or can be used
+together, or if some chip selects are hardwired to be FAST and others are SLOW
+by design.
+
+The XMEM registers are totally undocumented but could be partially decoded
+because the Cypress AN49576 Antioch Westbridge apparently has suspiciously
+similar register layout, see: http://www.cypress.com/file/105771/download
+
+Required properties:
+- compatible: should be one of:
+ "qcom,msm8660-ebi2"
+ "qcom,apq8060-ebi2"
+- #address-cells: shoule be <2>: the first cell is the chipselect,
+ the second cell is the offset inside the memory range
+- #size-cells: should be <1>
+- ranges: should be set to:
+ ranges = <0 0x0 0x1a800000 0x00800000>,
+ <1 0x0 0x1b000000 0x00800000>,
+ <2 0x0 0x1b800000 0x00800000>,
+ <3 0x0 0x1d000000 0x08000000>,
+ <4 0x0 0x1c800000 0x00800000>,
+ <5 0x0 0x1c000000 0x00800000>;
+- reg: two ranges of registers: EBI2 config and XMEM config areas
+- reg-names: should be "ebi2", "xmem"
+- clocks: two clocks, EBI_2X and EBI
+- clock-names: shoule be "ebi2x", "ebi2"
+
+Optional subnodes:
+- Nodes inside the EBI2 will be considered device nodes.
+
+The following optional properties are properties that can be tagged onto
+any device subnode. We are assuming that there can be only ONE device per
+chipselect subnode, else the properties will become ambigous.
+
+Optional properties arrays for SLOW chip selects:
+- qcom,xmem-recovery-cycles: recovery cycles is the time the memory continues to
+ drive the data bus after OE is de-asserted, in order to avoid contention on
+ the data bus. They are inserted when reading one CS and switching to another
+ CS or read followed by write on the same CS. Valid values 0 thru 15. Minimum
+ value is actually 1, so a value of 0 will still yield 1 recovery cycle.
+- qcom,xmem-write-hold-cycles: write hold cycles, these are extra cycles
+ inserted after every write minimum 1. The data out is driven from the time
+ WE is asserted until CS is asserted. With a hold of 1 (value = 0), the CS
+ stays active for 1 extra cycle etc. Valid values 0 thru 15.
+- qcom,xmem-write-delta-cycles: initial latency for write cycles inserted for
+ the first write to a page or burst memory. Valid values 0 thru 255.
+- qcom,xmem-read-delta-cycles: initial latency for read cycles inserted for the
+ first read to a page or burst memory. Valid values 0 thru 255.
+- qcom,xmem-write-wait-cycles: number of wait cycles for every write access, 0=1
+ cycle. Valid values 0 thru 15.
+- qcom,xmem-read-wait-cycles: number of wait cycles for every read access, 0=1
+ cycle. Valid values 0 thru 15.
+
+Optional properties arrays for FAST chip selects:
+- qcom,xmem-address-hold-enable: this is a boolean property stating that we
+ shall hold the address for an extra cycle to meet hold time requirements
+ with ADV assertion.
+- qcom,xmem-adv-to-oe-recovery-cycles: the number of cycles elapsed before an OE
+ assertion, with respect to the cycle where ADV (address valid) is asserted.
+ 2 means 2 cycles between ADV and OE. Valid values 0, 1, 2 or 3.
+- qcom,xmem-read-hold-cycles: the length in cycles of the first segment of a
+ read transfer. For a single read trandfer this will be the time from CS
+ assertion to OE assertion. Valid values 0 thru 15.
+
+
+Example:
+
+ebi2@1a100000 {
+ compatible = "qcom,apq8060-ebi2";
+ #address-cells = <2>;
+ #size-cells = <1>;
+ ranges = <0 0x0 0x1a800000 0x00800000>,
+ <1 0x0 0x1b000000 0x00800000>,
+ <2 0x0 0x1b800000 0x00800000>,
+ <3 0x0 0x1d000000 0x08000000>,
+ <4 0x0 0x1c800000 0x00800000>,
+ <5 0x0 0x1c000000 0x00800000>;
+ reg = <0x1a100000 0x1000>, <0x1a110000 0x1000>;
+ reg-names = "ebi2", "xmem";
+ clocks = <&gcc EBI2_2X_CLK>, <&gcc EBI2_CLK>;
+ clock-names = "ebi2x", "ebi2";
+ /* Make sure to set up the pin control for the EBI2 */
+ pinctrl-names = "default";
+ pinctrl-0 = <&foo_ebi2_pins>;
+
+ foo-ebi2@2,0 {
+ compatible = "foo";
+ reg = <2 0x0 0x100>;
+ (...)
+ qcom,xmem-recovery-cycles = <0>;
+ qcom,xmem-write-hold-cycles = <3>;
+ qcom,xmem-write-delta-cycles = <31>;
+ qcom,xmem-read-delta-cycles = <28>;
+ qcom,xmem-write-wait-cycles = <9>;
+ qcom,xmem-read-wait-cycles = <9>;
+ };
+};
--- /dev/null
+/*
+ * Qualcomm External Bus Interface 2 (EBI2) driver
+ * an older version of the Qualcomm Parallel Interface Controller (QPIC)
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ * See the device tree bindings for this block for more details on the
+ * hardware.
+ */
+
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/bitops.h>
+
+/*
+ * CS0, CS1, CS4 and CS5 are two bits wide, CS2 and CS3 are one bit.
+ */
+#define EBI2_CS0_ENABLE_MASK BIT(0)|BIT(1)
+#define EBI2_CS1_ENABLE_MASK BIT(2)|BIT(3)
+#define EBI2_CS2_ENABLE_MASK BIT(4)
+#define EBI2_CS3_ENABLE_MASK BIT(5)
+#define EBI2_CS4_ENABLE_MASK BIT(6)|BIT(7)
+#define EBI2_CS5_ENABLE_MASK BIT(8)|BIT(9)
+#define EBI2_CSN_MASK GENMASK(9, 0)
+
+#define EBI2_XMEM_CFG 0x0000 /* Power management etc */
+
+/*
+ * SLOW CSn CFG
+ *
+ * Bits 31-28: RECOVERY recovery cycles (0 = 1, 1 = 2 etc) this is the time the
+ * memory continues to drive the data bus after OE is de-asserted.
+ * Inserted when reading one CS and switching to another CS or read
+ * followed by write on the same CS. Valid values 0 thru 15.
+ * Bits 27-24: WR_HOLD write hold cycles, these are extra cycles inserted after
+ * every write minimum 1. The data out is driven from the time WE is
+ * asserted until CS is asserted. With a hold of 1, the CS stays
+ * active for 1 extra cycle etc. Valid values 0 thru 15.
+ * Bits 23-16: WR_DELTA initial latency for write cycles inserted for the first
+ * write to a page or burst memory
+ * Bits 15-8: RD_DELTA initial latency for read cycles inserted for the first
+ * read to a page or burst memory
+ * Bits 7-4: WR_WAIT number of wait cycles for every write access, 0=1 cycle
+ * so 1 thru 16 cycles.
+ * Bits 3-0: RD_WAIT number of wait cycles for every read access, 0=1 cycle
+ * so 1 thru 16 cycles.
+ */
+#define EBI2_XMEM_CS0_SLOW_CFG 0x0008
+#define EBI2_XMEM_CS1_SLOW_CFG 0x000C
+#define EBI2_XMEM_CS2_SLOW_CFG 0x0010
+#define EBI2_XMEM_CS3_SLOW_CFG 0x0014
+#define EBI2_XMEM_CS4_SLOW_CFG 0x0018
+#define EBI2_XMEM_CS5_SLOW_CFG 0x001C
+
+#define EBI2_XMEM_RECOVERY_SHIFT 28
+#define EBI2_XMEM_WR_HOLD_SHIFT 24
+#define EBI2_XMEM_WR_DELTA_SHIFT 16
+#define EBI2_XMEM_RD_DELTA_SHIFT 8
+#define EBI2_XMEM_WR_WAIT_SHIFT 4
+#define EBI2_XMEM_RD_WAIT_SHIFT 0
+
+/*
+ * FAST CSn CFG
+ * Bits 31-28: ?
+ * Bits 27-24: RD_HOLD: the length in cycles of the first segment of a read
+ * transfer. For a single read trandfer this will be the time
+ * from CS assertion to OE assertion.
+ * Bits 18-24: ?
+ * Bits 17-16: ADV_OE_RECOVERY, the number of cycles elapsed before an OE
+ * assertion, with respect to the cycle where ADV is asserted.
+ * 2 means 2 cycles between ADV and OE. Values 0, 1, 2 or 3.
+ * Bits 5: ADDR_HOLD_ENA, The address is held for an extra cycle to meet
+ * hold time requirements with ADV assertion.
+ *
+ * The manual mentions "write precharge cycles" and "precharge cycles".
+ * We have not been able to figure out which bit fields these correspond to
+ * in the hardware, or what valid values exist. The current hypothesis is that
+ * this is something just used on the FAST chip selects. There is also a "byte
+ * device enable" flag somewhere for 8bit memories.
+ */
+#define EBI2_XMEM_CS0_FAST_CFG 0x0028
+#define EBI2_XMEM_CS1_FAST_CFG 0x002C
+#define EBI2_XMEM_CS2_FAST_CFG 0x0030
+#define EBI2_XMEM_CS3_FAST_CFG 0x0034
+#define EBI2_XMEM_CS4_FAST_CFG 0x0038
+#define EBI2_XMEM_CS5_FAST_CFG 0x003C
+
+#define EBI2_XMEM_RD_HOLD_SHIFT 24
+#define EBI2_XMEM_ADV_OE_RECOVERY_SHIFT 16
+#define EBI2_XMEM_ADDR_HOLD_ENA_SHIFT 5
+
+/**
+ * struct cs_data - struct with info on a chipselect setting
+ * @enable_mask: mask to enable the chipselect in the EBI2 config
+ * @slow_cfg0: offset to XMEMC slow CS config
+ * @fast_cfg1: offset to XMEMC fast CS config
+ */
+struct cs_data {
+ u32 enable_mask;
+ u16 slow_cfg;
+ u16 fast_cfg;
+};
+
+static const struct cs_data cs_info[] = {
+ {
+ /* CS0 */
+ .enable_mask = EBI2_CS0_ENABLE_MASK,
+ .slow_cfg = EBI2_XMEM_CS0_SLOW_CFG,
+ .fast_cfg = EBI2_XMEM_CS0_FAST_CFG,
+ },
+ {
+ /* CS1 */
+ .enable_mask = EBI2_CS1_ENABLE_MASK,
+ .slow_cfg = EBI2_XMEM_CS1_SLOW_CFG,
+ .fast_cfg = EBI2_XMEM_CS1_FAST_CFG,
+ },
+ {
+ /* CS2 */
+ .enable_mask = EBI2_CS2_ENABLE_MASK,
+ .slow_cfg = EBI2_XMEM_CS2_SLOW_CFG,
+ .fast_cfg = EBI2_XMEM_CS2_FAST_CFG,
+ },
+ {
+ /* CS3 */
+ .enable_mask = EBI2_CS3_ENABLE_MASK,
+ .slow_cfg = EBI2_XMEM_CS3_SLOW_CFG,
+ .fast_cfg = EBI2_XMEM_CS3_FAST_CFG,
+ },
+ {
+ /* CS4 */
+ .enable_mask = EBI2_CS4_ENABLE_MASK,
+ .slow_cfg = EBI2_XMEM_CS4_SLOW_CFG,
+ .fast_cfg = EBI2_XMEM_CS4_FAST_CFG,
+ },
+ {
+ /* CS5 */
+ .enable_mask = EBI2_CS5_ENABLE_MASK,
+ .slow_cfg = EBI2_XMEM_CS5_SLOW_CFG,
+ .fast_cfg = EBI2_XMEM_CS5_FAST_CFG,
+ },
+};
+
+/**
+ * struct ebi2_xmem_prop - describes an XMEM config property
+ * @prop: the device tree binding name
+ * @max: maximum value for the property
+ * @slowreg: true if this property is in the SLOW CS config register
+ * else it is assumed to be in the FAST config register
+ * @shift: the bit field start in the SLOW or FAST register for this
+ * property
+ */
+struct ebi2_xmem_prop {
+ const char *prop;
+ u32 max;
+ bool slowreg;
+ u16 shift;
+};
+
+static const struct ebi2_xmem_prop xmem_props[] = {
+ {
+ .prop = "qcom,xmem-recovery-cycles",
+ .max = 15,
+ .slowreg = true,
+ .shift = EBI2_XMEM_RECOVERY_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-write-hold-cycles",
+ .max = 15,
+ .slowreg = true,
+ .shift = EBI2_XMEM_WR_HOLD_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-write-delta-cycles",
+ .max = 255,
+ .slowreg = true,
+ .shift = EBI2_XMEM_WR_DELTA_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-read-delta-cycles",
+ .max = 255,
+ .slowreg = true,
+ .shift = EBI2_XMEM_RD_DELTA_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-write-wait-cycles",
+ .max = 15,
+ .slowreg = true,
+ .shift = EBI2_XMEM_WR_WAIT_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-read-wait-cycles",
+ .max = 15,
+ .slowreg = true,
+ .shift = EBI2_XMEM_RD_WAIT_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-address-hold-enable",
+ .max = 1, /* boolean prop */
+ .slowreg = false,
+ .shift = EBI2_XMEM_ADDR_HOLD_ENA_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-adv-to-oe-recovery-cycles",
+ .max = 3,
+ .slowreg = false,
+ .shift = EBI2_XMEM_ADV_OE_RECOVERY_SHIFT,
+ },
+ {
+ .prop = "qcom,xmem-read-hold-cycles",
+ .max = 15,
+ .slowreg = false,
+ .shift = EBI2_XMEM_RD_HOLD_SHIFT,
+ },
+};
+
+static void qcom_ebi2_setup_chipselect(struct device_node *np,
+ struct device *dev,
+ void __iomem *ebi2_base,
+ void __iomem *ebi2_xmem,
+ u32 csindex)
+{
+ const struct cs_data *csd;
+ u32 slowcfg, fastcfg;
+ u32 val;
+ int ret;
+ int i;
+
+ csd = &cs_info[csindex];
+ val = readl(ebi2_base);
+ val |= csd->enable_mask;
+ writel(val, ebi2_base);
+ dev_dbg(dev, "enabled CS%u\n", csindex);
+
+ /* Next set up the XMEMC */
+ slowcfg = 0;
+ fastcfg = 0;
+
+ for (i = 0; i < ARRAY_SIZE(xmem_props); i++) {
+ const struct ebi2_xmem_prop *xp = &xmem_props[i];
+
+ /* All are regular u32 values */
+ ret = of_property_read_u32(np, xp->prop, &val);
+ if (ret) {
+ dev_dbg(dev, "could not read %s for CS%d\n",
+ xp->prop, csindex);
+ continue;
+ }
+
+ /* First check boolean props */
+ if (xp->max == 1 && val) {
+ if (xp->slowreg)
+ slowcfg |= BIT(xp->shift);
+ else
+ fastcfg |= BIT(xp->shift);
+ dev_dbg(dev, "set %s flag\n", xp->prop);
+ continue;
+ }
+
+ /* We're dealing with an u32 */
+ if (val > xp->max) {
+ dev_err(dev,
+ "too high value for %s: %u, capped at %u\n",
+ xp->prop, val, xp->max);
+ val = xp->max;
+ }
+ if (xp->slowreg)
+ slowcfg |= (val << xp->shift);
+ else
+ fastcfg |= (val << xp->shift);
+ dev_dbg(dev, "set %s to %u\n", xp->prop, val);
+ }
+
+ dev_info(dev, "CS%u: SLOW CFG 0x%08x, FAST CFG 0x%08x\n",
+ csindex, slowcfg, fastcfg);
+
+ if (slowcfg)
+ writel(slowcfg, ebi2_xmem + csd->slow_cfg);
+ if (fastcfg)
+ writel(fastcfg, ebi2_xmem + csd->fast_cfg);
+}
+
+static int qcom_ebi2_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *child;
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ void __iomem *ebi2_base;
+ void __iomem *ebi2_xmem;
+ struct clk *ebi2xclk;
+ struct clk *ebi2clk;
+ bool have_children = false;
+ u32 val;
+ int ret;
+
+ ebi2xclk = devm_clk_get(dev, "ebi2x");
+ if (IS_ERR(ebi2xclk))
+ return PTR_ERR(ebi2xclk);
+
+ ret = clk_prepare_enable(ebi2xclk);
+ if (ret) {
+ dev_err(dev, "could not enable EBI2X clk (%d)\n", ret);
+ return ret;
+ }
+
+ ebi2clk = devm_clk_get(dev, "ebi2");
+ if (IS_ERR(ebi2clk)) {
+ ret = PTR_ERR(ebi2clk);
+ goto err_disable_2x_clk;
+ }
+
+ ret = clk_prepare_enable(ebi2clk);
+ if (ret) {
+ dev_err(dev, "could not enable EBI2 clk\n");
+ goto err_disable_2x_clk;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ ebi2_base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(ebi2_base)) {
+ ret = PTR_ERR(ebi2_base);
+ goto err_disable_clk;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ ebi2_xmem = devm_ioremap_resource(dev, res);
+ if (IS_ERR(ebi2_xmem)) {
+ ret = PTR_ERR(ebi2_xmem);
+ goto err_disable_clk;
+ }
+
+ /* Allegedly this turns the power save mode off */
+ writel(0UL, ebi2_xmem + EBI2_XMEM_CFG);
+
+ /* Disable all chipselects */
+ val = readl(ebi2_base);
+ val &= ~EBI2_CSN_MASK;
+ writel(val, ebi2_base);
+
+ /* Walk over the child nodes and see what chipselects we use */
+ for_each_available_child_of_node(np, child) {
+ u32 csindex;
+
+ /* Figure out the chipselect */
+ ret = of_property_read_u32(child, "reg", &csindex);
+ if (ret)
+ return ret;
+
+ if (csindex > 5) {
+ dev_err(dev,
+ "invalid chipselect %u, we only support 0-5\n",
+ csindex);
+ continue;
+ }
+
+ qcom_ebi2_setup_chipselect(child,
+ dev,
+ ebi2_base,
+ ebi2_xmem,
+ csindex);
+
+ /* We have at least one child */
+ have_children = true;
+ }
+
+ if (have_children)
+ return of_platform_default_populate(np, NULL, dev);
+ return 0;
+
+err_disable_clk:
+ clk_disable_unprepare(ebi2clk);
+err_disable_2x_clk:
+ clk_disable_unprepare(ebi2xclk);
+
+ return ret;
+}
+
+static const struct of_device_id qcom_ebi2_of_match[] = {
+ { .compatible = "qcom,msm8660-ebi2", },
+ { .compatible = "qcom,apq8060-ebi2", },
+ { }
+};
+
+static struct platform_driver qcom_ebi2_driver = {
+ .probe = qcom_ebi2_probe,
+ .driver = {
+ .name = "qcom-ebi2",
+ .of_match_table = qcom_ebi2_of_match,
+ },
+};
+module_platform_driver(qcom_ebi2_driver);
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_DESCRIPTION("Qualcomm EBI2 driver");
+MODULE_LICENSE("GPL");
projects / linux.git / commitdiff