summaryrefslogtreecommitdiffstats
path: root/drivers/bus/qcom-ebi2.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/bus/qcom-ebi2.c')
-rw-r--r--drivers/bus/qcom-ebi2.c406
1 files changed, 406 insertions, 0 deletions
diff --git a/drivers/bus/qcom-ebi2.c b/drivers/bus/qcom-ebi2.c
new file mode 100644
index 000000000..663c82749
--- /dev/null
+++ b/drivers/bus/qcom-ebi2.c
@@ -0,0 +1,406 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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>
+ *
+ * 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/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_cfg: offset to XMEMC slow CS config
+ * @fast_cfg: 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) {
+ of_node_put(child);
+ 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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-30 23:37:11 +0000