[PATCH v3 8/8] memory: tegra: Introduce Tegra20 EMC driver

Dmitry Osipenko
2018-06-17T15:00:48Z

Introduce driver for the External Memory Controller (EMC) found on Tegra20
chips, which controls the external DRAM on the board. The purpose of this
driver is to program memory timing for external memory on the EMC clock
rate change.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
---
drivers/memory/tegra/Kconfig | 10 +
drivers/memory/tegra/Makefile | 1 +
drivers/memory/tegra/tegra20-emc.c | 574 +++++++++++++++++++++++++++++
3 files changed, 585 insertions(+)
create mode 100644 drivers/memory/tegra/tegra20-emc.c

diff --git a/drivers/memory/tegra/Kconfig b/drivers/memory/tegra/Kconfig
index 6d74e499e18d..34e0b70f5c5f 100644
--- a/drivers/memory/tegra/Kconfig
+++ b/drivers/memory/tegra/Kconfig
@@ -6,6 +6,16 @@ config TEGRA_MC
This driver supports the Memory Controller (MC) hardware found on
NVIDIA Tegra SoCs.

+config TEGRA20_EMC
+ bool "NVIDIA Tegra20 External Memory Controller driver"
+ default y
+ depends on ARCH_TEGRA_2x_SOC
+ help
+ This driver is for the External Memory Controller (EMC) found on
+ Tegra20 chips. The EMC controls the external DRAM on the board.
+ This driver is required to change memory timings / clock rate for
+ external memory.
+
config TEGRA124_EMC
bool "NVIDIA Tegra124 External Memory Controller driver"
default y
diff --git a/drivers/memory/tegra/Makefile b/drivers/memory/tegra/Makefile
index 94ab16ba075b..3971a6b7c487 100644
--- a/drivers/memory/tegra/Makefile
+++ b/drivers/memory/tegra/Makefile
@@ -10,5 +10,6 @@ tegra-mc-$(CONFIG_ARCH_TEGRA_210_SOC) += tegra210.o

obj-$(CONFIG_TEGRA_MC) += tegra-mc.o

+obj-$(CONFIG_TEGRA20_EMC) += tegra20-emc.o
obj-$(CONFIG_TEGRA124_EMC) += tegra124-emc.o
obj-$(CONFIG_ARCH_TEGRA_186_SOC) += tegra186.o
diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c
new file mode 100644
index 000000000000..b4a0066bdf4f
--- /dev/null
+++ b/drivers/memory/tegra/tegra20-emc.c
@@ -0,0 +1,574 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tegra20 External Memory Controller driver
+ *
+ * Author: Dmitry Osipenko <digetx@gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/sort.h>
+#include <linux/types.h>
+
+#include <soc/tegra/fuse.h>
+
+#define EMC_INTSTATUS 0x000
+#define EMC_INTMASK 0x004
+#define EMC_TIMING_CONTROL 0x028
+#define EMC_RC 0x02c
+#define EMC_RFC 0x030
+#define EMC_RAS 0x034
+#define EMC_RP 0x038
+#define EMC_R2W 0x03c
+#define EMC_W2R 0x040
+#define EMC_R2P 0x044
+#define EMC_W2P 0x048
+#define EMC_RD_RCD 0x04c
+#define EMC_WR_RCD 0x050
+#define EMC_RRD 0x054
+#define EMC_REXT 0x058
+#define EMC_WDV 0x05c
+#define EMC_QUSE 0x060
+#define EMC_QRST 0x064
+#define EMC_QSAFE 0x068
+#define EMC_RDV 0x06c
+#define EMC_REFRESH 0x070
+#define EMC_BURST_REFRESH_NUM 0x074
+#define EMC_PDEX2WR 0x078
+#define EMC_PDEX2RD 0x07c
+#define EMC_PCHG2PDEN 0x080
+#define EMC_ACT2PDEN 0x084
+#define EMC_AR2PDEN 0x088
+#define EMC_RW2PDEN 0x08c
+#define EMC_TXSR 0x090
+#define EMC_TCKE 0x094
+#define EMC_TFAW 0x098
+#define EMC_TRPAB 0x09c
+#define EMC_TCLKSTABLE 0x0a0
+#define EMC_TCLKSTOP 0x0a4
+#define EMC_TREFBW 0x0a8
+#define EMC_QUSE_EXTRA 0x0ac
+#define EMC_ODT_WRITE 0x0b0
+#define EMC_ODT_READ 0x0b4
+#define EMC_FBIO_CFG5 0x104
+#define EMC_FBIO_CFG6 0x114
+#define EMC_AUTO_CAL_INTERVAL 0x2a8
+#define EMC_CFG_2 0x2b8
+#define EMC_CFG_DIG_DLL 0x2bc
+#define EMC_DLL_XFORM_DQS 0x2c0
+#define EMC_DLL_XFORM_QUSE 0x2c4
+#define EMC_ZCAL_REF_CNT 0x2e0
+#define EMC_ZCAL_WAIT_CNT 0x2e4
+#define EMC_CFG_CLKTRIM_0 0x2d0
+#define EMC_CFG_CLKTRIM_1 0x2d4
+#define EMC_CFG_CLKTRIM_2 0x2d8
+
+#define EMC_CLKCHANGE_REQ_ENABLE BIT(0)
+#define EMC_CLKCHANGE_PD_ENABLE BIT(1)
+#define EMC_CLKCHANGE_SR_ENABLE BIT(2)
+
+#define EMC_TIMING_UPDATE BIT(0)
+
+#define EMC_CLKCHANGE_COMPLETE_INT BIT(4)
+
+static const u16 emc_timing_registers[] = {
+ EMC_RC,
+ EMC_RFC,
+ EMC_RAS,
+ EMC_RP,
+ EMC_R2W,
+ EMC_W2R,
+ EMC_R2P,
+ EMC_W2P,
+ EMC_RD_RCD,
+ EMC_WR_RCD,
+ EMC_RRD,
+ EMC_REXT,
+ EMC_WDV,
+ EMC_QUSE,
+ EMC_QRST,
+ EMC_QSAFE,
+ EMC_RDV,
+ EMC_REFRESH,
+ EMC_BURST_REFRESH_NUM,
+ EMC_PDEX2WR,
+ EMC_PDEX2RD,
+ EMC_PCHG2PDEN,
+ EMC_ACT2PDEN,
+ EMC_AR2PDEN,
+ EMC_RW2PDEN,
+ EMC_TXSR,
+ EMC_TCKE,
+ EMC_TFAW,
+ EMC_TRPAB,
+ EMC_TCLKSTABLE,
+ EMC_TCLKSTOP,
+ EMC_TREFBW,
+ EMC_QUSE_EXTRA,
+ EMC_FBIO_CFG6,
+ EMC_ODT_WRITE,
+ EMC_ODT_READ,
+ EMC_FBIO_CFG5,
+ EMC_CFG_DIG_DLL,
+ EMC_DLL_XFORM_DQS,
+ EMC_DLL_XFORM_QUSE,
+ EMC_ZCAL_REF_CNT,
+ EMC_ZCAL_WAIT_CNT,
+ EMC_AUTO_CAL_INTERVAL,
+ EMC_CFG_CLKTRIM_0,
+ EMC_CFG_CLKTRIM_1,
+ EMC_CFG_CLKTRIM_2,
+};
+
+struct emc_timing {
+ unsigned long rate;
+ u32 data[ARRAY_SIZE(emc_timing_registers)];
+};
+
+struct tegra_emc {
+ struct device *dev;
+ struct completion clk_handshake_complete;
+ struct notifier_block clk_nb;
+ struct clk *backup_clk;
+ struct clk *emc_mux;
+ struct clk *pll_m;
+ struct clk *clk;
+ void __iomem *regs;
+
+ struct emc_timing *timings;
+ unsigned int num_timings;
+};
+
+static irqreturn_t tegra_emc_isr(int irq, void *data)
+{
+ struct tegra_emc *emc = data;
+ u32 intmask = EMC_CLKCHANGE_COMPLETE_INT;
+ u32 status;
+
+ status = readl_relaxed(emc->regs + EMC_INTSTATUS) & intmask;
+ if (!status)
+ return IRQ_NONE;
+
+ /* clear interrupts */
+ writel_relaxed(status, emc->regs + EMC_INTSTATUS);
+
+ /* notify about EMC-CAR handshake completion */
+ complete(&emc->clk_handshake_complete);
+
+ return IRQ_HANDLED;
+}
+
+static struct emc_timing *tegra_emc_find_timing(struct tegra_emc *emc,
+ unsigned long rate)
+{
+ struct emc_timing *timing = NULL;
+ unsigned int i;
+
+ for (i = 0; i < emc->num_timings; i++) {
+ if (emc->timings[i].rate >= rate) {
+ timing = &emc->timings[i];
+ break;
+ }
+ }
+
+ if (!timing) {
+ dev_err(emc->dev, "no timing for rate %lu\n", rate);
+ return NULL;
+ }
+
+ return timing;
+}
+
+static int emc_prepare_timing_change(struct tegra_emc *emc, unsigned long rate)
+{
+ struct emc_timing *timing = tegra_emc_find_timing(emc, rate);
+ unsigned int i;
+
+ if (!timing)
+ return -EINVAL;
+
+ dev_dbg(emc->dev, "%s: using timing rate %lu for requested rate %lu\n",
+ __func__, timing->rate, rate);
+
+ /* program shadow registers */
+ for (i = 0; i < ARRAY_SIZE(timing->data); i++)
+ writel_relaxed(timing->data[i],
+ emc->regs + emc_timing_registers[i]);
+
+ /* wait until programming has settled */
+ readl_relaxed(emc->regs + emc_timing_registers[0]);
+
+ reinit_completion(&emc->clk_handshake_complete);
+
+ return 0;
+}
+
+static int emc_complete_timing_change(struct tegra_emc *emc, bool flush)
+{
+ long timeout;
+
+ dev_dbg(emc->dev, "%s: flush %d\n", __func__, flush);
+
+ if (flush) {
+ /* manually initiate memory timing update */
+ writel_relaxed(EMC_TIMING_UPDATE,
+ emc->regs + EMC_TIMING_CONTROL);
+ return 0;
+ }
+
+ timeout = wait_for_completion_timeout(&emc->clk_handshake_complete,
+ usecs_to_jiffies(100));
+ if (timeout == 0) {
+ dev_err(emc->dev, "EMC-CAR handshake failed\n");
+ return -EIO;
+ } else if (timeout < 0) {
+ dev_err(emc->dev, "failed to wait for EMC-CAR handshake: %ld\n",
+ timeout);
+ return timeout;
+ }
+
+ return 0;
+}
+
+static int tegra_emc_clk_change_notify(struct notifier_block *nb,
+ unsigned long msg, void *data)
+{
+ struct tegra_emc *emc = container_of(nb, struct tegra_emc, clk_nb);
+ struct clk_notifier_data *cnd = data;
+ int err;
+
+ switch (msg) {
+ case PRE_RATE_CHANGE:
+ err = emc_prepare_timing_change(emc, cnd->new_rate);
+ break;
+
+ case ABORT_RATE_CHANGE:
+ err = emc_prepare_timing_change(emc, cnd->old_rate);
+ if (err)
+ break;
+
+ err = emc_complete_timing_change(emc, true);
+ break;
+
+ case POST_RATE_CHANGE:
+ err = emc_complete_timing_change(emc, false);
+ break;
+
+ default:
+ return NOTIFY_DONE;
+ }
+
+ return notifier_from_errno(err);
+}
+
+static int load_one_timing_from_dt(struct tegra_emc *emc,
+ struct emc_timing *timing,
+ struct device_node *node)
+{
+ u32 rate;
+ int err;
+
+ if (!of_device_is_compatible(node, "nvidia,tegra20-emc-table")) {
+ dev_err(emc->dev, "incompatible DT node: %pOF\n", node);
+ return -EINVAL;
+ }
+
+ err = of_property_read_u32(node, "clock-frequency", &rate);
+ if (err) {
+ dev_err(emc->dev, "timing %pOF: failed to read rate: %d\n",
+ node, err);
+ return err;
+ }
+
+ err = of_property_read_u32_array(node, "nvidia,emc-registers",
+ timing->data,
+ ARRAY_SIZE(emc_timing_registers));
+ if (err) {
+ dev_err(emc->dev,
+ "timing %pOF: failed to read emc timing data: %d\n",
+ node, err);
+ return err;
+ }
+
+ /*
+ * The EMC clock rate is twice the bus rate, and the bus rate is
+ * measured in kHz.
+ */
+ timing->rate = rate * 2 * 1000;
+
+ dev_dbg(emc->dev, "%s: %pOF: EMC rate %lu\n",
+ __func__, node, timing->rate);
+
+ return 0;
+}
+
+static int cmp_timings(const void *_a, const void *_b)
+{
+ const struct emc_timing *a = _a;
+ const struct emc_timing *b = _b;
+
+ if (a->rate < b->rate)
+ return -1;
+
+ if (a->rate > b->rate)
+ return 1;
+
+ return 0;
+}
+
+static int tegra_emc_load_timings_from_dt(struct tegra_emc *emc,
+ struct device_node *node)
+{
+ struct device_node *child;
+ struct emc_timing *timing;
+ int child_count;
+ int err;
+
+ child_count = of_get_child_count(node);
+ if (!child_count) {
+ dev_err(emc->dev, "no memory timings in DT node: %pOF\n", node);
+ return -EINVAL;
+ }
+
+ emc->timings = devm_kcalloc(emc->dev, child_count, sizeof(*timing),
+ GFP_KERNEL);
+ if (!emc->timings)
+ return -ENOMEM;
+
+ emc->num_timings = child_count;
+ timing = emc->timings;
+
+ for_each_child_of_node(node, child) {
+ err = load_one_timing_from_dt(emc, timing++, child);
+ of_node_put(child);
+ if (err)
+ return err;
+ }
+
+ sort(emc->timings, emc->num_timings, sizeof(*timing), cmp_timings,
+ NULL);
+
+ return 0;
+}
+
+static struct device_node *
+tegra_emc_find_node_by_ram_code(struct device *dev)
+{
+ struct device_node *np;
+ u32 value, ram_code;
+ int err;
+
+ if (!of_property_read_bool(dev->of_node, "nvidia,use-ram-code"))
+ return of_node_get(dev->of_node);
+
+ ram_code = tegra_read_ram_code();
+ np = dev->of_node;
+
+ for_each_node_by_name(np, "emc-tables") {
+ err = of_property_read_u32(np, "nvidia,ram-code", &value);
+ if (err || value != ram_code) {
+ of_node_put(np);
+ continue;
+ }
+
+ return np;
+ }
+
+ dev_err(dev, "no memory timings for RAM code %u found in device tree\n",
+ ram_code);
+
+ return NULL;
+}
+
+static int emc_setup_hw(struct tegra_emc *emc)
+{
+ u32 emc_cfg;
+
+ emc_cfg = readl_relaxed(emc->regs + EMC_CFG_2);
+
+ /*
+ * Depending on a memory type, DRAM should enter either self-refresh
+ * or power-down state on EMC clock change.
+ */
+ if (!(emc_cfg & EMC_CLKCHANGE_PD_ENABLE) &&
+ !(emc_cfg & EMC_CLKCHANGE_SR_ENABLE))
+ {
+ dev_err(emc->dev,
+ "bootloader didn't specify DRAM auto-suspend mode\n");
+ return -EINVAL;
+ }
+
+ /* allow EMC and CAR to handshake on PLL divider/source changes */
+ emc_cfg |= EMC_CLKCHANGE_REQ_ENABLE;
+ writel_relaxed(emc_cfg, emc->regs + EMC_CFG_2);
+
+ /* initialize interrupt */
+ writel_relaxed(EMC_CLKCHANGE_COMPLETE_INT, emc->regs + EMC_INTMASK);
+ writel_relaxed(EMC_CLKCHANGE_COMPLETE_INT, emc->regs + EMC_INTSTATUS);
+
+ return 0;
+}
+
+static int emc_init(struct tegra_emc *emc, unsigned long rate)
+{
+ int err, ret;
+
+ err = clk_set_parent(emc->emc_mux, emc->backup_clk);
+ if (err) {
+ dev_err(emc->dev,
+ "failed to reparent to backup source: %d\n", err);
+ return err;
+ }
+
+ ret = clk_set_rate(emc->pll_m, rate);
+ if (ret)
+ dev_err(emc->dev,
+ "failed to change pll_m rate: %d\n", ret);
+
+ err = clk_set_parent(emc->emc_mux, emc->pll_m);
+ if (err) {
+ dev_err(emc->dev,
+ "failed to reparent to pll_m: %d\n", err);
+ return err;
+ }
+
+ return ret;
+}
+
+static int tegra_emc_probe(struct platform_device *pdev)
+{
+ struct device_node *np;
+ struct tegra_emc *emc;
+ struct resource *res;
+ int irq, err;
+
+ /* driver has nothing to do in a case of memory timing absence */
+ if (of_get_child_count(pdev->dev.of_node) == 0) {
+ dev_info(&pdev->dev,
+ "EMC device tree node doesn't have memory timings\n");
+ return 0;
+ }
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "interrupt not specified\n");
+ dev_err(&pdev->dev, "please update your device tree\n");
+ return irq;
+ }
+
+ np = tegra_emc_find_node_by_ram_code(&pdev->dev);
+ if (!np)
+ return -EINVAL;
+
+ emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
+ if (!emc) {
+ of_node_put(np);
+ return -ENOMEM;
+ }
+
+ init_completion(&emc->clk_handshake_complete);
+ emc->clk_nb.notifier_call = tegra_emc_clk_change_notify;
+ emc->dev = &pdev->dev;
+
+ err = tegra_emc_load_timings_from_dt(emc, np);
+ of_node_put(np);
+ if (err)
+ return err;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ emc->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(emc->regs))
+ return PTR_ERR(emc->regs);
+
+ err = emc_setup_hw(emc);
+ if (err)
+ return err;
+
+ err = devm_request_irq(&pdev->dev, irq, tegra_emc_isr, 0,
+ dev_name(&pdev->dev), emc);
+ if (err) {
+ dev_err(&pdev->dev, "failed to request IRQ#%u: %d\n", irq, err);
+ return err;
+ }
+
+ emc->clk = devm_clk_get(&pdev->dev, "emc");
+ if (IS_ERR(emc->clk)) {
+ err = PTR_ERR(emc->clk);
+ dev_err(&pdev->dev, "failed to get emc clock: %d\n", err);
+ return err;
+ }
+
+ emc->pll_m = clk_get_sys(NULL, "pll_m");
+ if (IS_ERR(emc->pll_m)) {
+ err = PTR_ERR(emc->pll_m);
+ dev_err(&pdev->dev, "failed to get pll_m clock: %d\n", err);
+ return err;
+ }
+
+ emc->backup_clk = clk_get_sys(NULL, "pll_p");
+ if (IS_ERR(emc->backup_clk)) {
+ err = PTR_ERR(emc->backup_clk);
+ dev_err(&pdev->dev, "failed to get pll_p clock: %d\n", err);
+ goto put_pll_m;
+ }
+
+ emc->emc_mux = clk_get_parent(emc->clk);
+ if (IS_ERR(emc->emc_mux)) {
+ err = PTR_ERR(emc->emc_mux);
+ dev_err(&pdev->dev, "failed to get emc_mux clock: %d\n", err);
+ goto put_backup;
+ }
+
+ err = clk_notifier_register(emc->clk, &emc->clk_nb);
+ if (err) {
+ dev_err(&pdev->dev, "failed to register clk notifier: %d\n",
+ err);
+ goto put_backup;
+ }
+
+ /* set DRAM clock rate to maximum */
+ err = emc_init(emc, emc->timings[emc->num_timings - 1].rate);
+ if (err) {
+ dev_err(&pdev->dev, "failed to initialize EMC clock rate: %d\n",
+ err);
+ goto unreg_notifier;
+ }
+
+ return 0;
+
+unreg_notifier:
+ clk_notifier_unregister(emc->clk, &emc->clk_nb);
+put_backup:
+ clk_put(emc->backup_clk);
+put_pll_m:
+ clk_put(emc->pll_m);
+
+ return err;
+}
+
+static const struct of_device_id tegra_emc_of_match[] = {
+ { .compatible = "nvidia,tegra20-emc", },
+ {},
+};
+
+static struct platform_driver tegra_emc_driver = {
+ .probe = tegra_emc_probe,
+ .driver = {
+ .name = "tegra20-emc",
+ .of_match_table = tegra_emc_of_match,
+ .suppress_bind_attrs = true,
+ },
+};
+
+static int __init tegra_emc_init(void)
+{
+ return platform_driver_register(&tegra_emc_driver);
+}
+subsys_initcall(tegra_emc_init);
--
2.17.1