--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2019-2020 ARM Limited or its affiliates. */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/workqueue.h>
+#include <linux/circ_buf.h>
+#include <linux/completion.h>
+#include <linux/of.h>
+#include <linux/bitfield.h>
+
+#include "cctrng.h"
+
+#define CC_REG_LOW(name) (name ## _BIT_SHIFT)
+#define CC_REG_HIGH(name) (CC_REG_LOW(name) + name ## _BIT_SIZE - 1)
+#define CC_GENMASK(name) GENMASK(CC_REG_HIGH(name), CC_REG_LOW(name))
+
+#define CC_REG_FLD_GET(reg_name, fld_name, reg_val) \
+ (FIELD_GET(CC_GENMASK(CC_ ## reg_name ## _ ## fld_name), reg_val))
+
+#define CC_HW_RESET_LOOP_COUNT 10
+#define CC_TRNG_SUSPEND_TIMEOUT 3000
+
+/* data circular buffer in words must be:
+ * - of a power-of-2 size (limitation of circ_buf.h macros)
+ * - at least 6, the size generated in the EHR according to HW implementation
+ */
+#define CCTRNG_DATA_BUF_WORDS 32
+
+/* The timeout for the TRNG operation should be calculated with the formula:
+ * Timeout = EHR_NUM * VN_COEFF * EHR_LENGTH * SAMPLE_CNT * SCALE_VALUE
+ * while:
+ * - SAMPLE_CNT is input value from the characterisation process
+ * - all the rest are constants
+ */
+#define EHR_NUM 1
+#define VN_COEFF 4
+#define EHR_LENGTH CC_TRNG_EHR_IN_BITS
+#define SCALE_VALUE 2
+#define CCTRNG_TIMEOUT(smpl_cnt) \
+ (EHR_NUM * VN_COEFF * EHR_LENGTH * smpl_cnt * SCALE_VALUE)
+
+struct cctrng_drvdata {
+ struct platform_device *pdev;
+ void __iomem *cc_base;
+ struct clk *clk;
+ struct hwrng rng;
+ u32 active_rosc;
+ /* Sampling interval for each ring oscillator:
+ * count of ring oscillator cycles between consecutive bits sampling.
+ * Value of 0 indicates non-valid rosc
+ */
+ u32 smpl_ratio[CC_TRNG_NUM_OF_ROSCS];
+
+ u32 data_buf[CCTRNG_DATA_BUF_WORDS];
+ struct circ_buf circ;
+ struct work_struct compwork;
+ struct work_struct startwork;
+
+ /* pending_hw - 1 when HW is pending, 0 when it is idle */
+ atomic_t pending_hw;
+
+ /* protects against multiple concurrent consumers of data_buf */
+ spinlock_t read_lock;
+};
+
+
+/* functions for write/read CC registers */
+static inline void cc_iowrite(struct cctrng_drvdata *drvdata, u32 reg, u32 val)
+{
+ iowrite32(val, (drvdata->cc_base + reg));
+}
+static inline u32 cc_ioread(struct cctrng_drvdata *drvdata, u32 reg)
+{
+ return ioread32(drvdata->cc_base + reg);
+}
+
+
+static int cc_trng_pm_get(struct device *dev)
+{
+ int rc = 0;
+
+ rc = pm_runtime_get_sync(dev);
+
+ /* pm_runtime_get_sync() can return 1 as a valid return code */
+ return (rc == 1 ? 0 : rc);
+}
+
+static void cc_trng_pm_put_suspend(struct device *dev)
+{
+ int rc = 0;
+
+ pm_runtime_mark_last_busy(dev);
+ rc = pm_runtime_put_autosuspend(dev);
+ if (rc)
+ dev_err(dev, "pm_runtime_put_autosuspend returned %x\n", rc);
+}
+
+static int cc_trng_pm_init(struct cctrng_drvdata *drvdata)
+{
+ struct device *dev = &(drvdata->pdev->dev);
+
+ /* must be before the enabling to avoid redundant suspending */
+ pm_runtime_set_autosuspend_delay(dev, CC_TRNG_SUSPEND_TIMEOUT);
+ pm_runtime_use_autosuspend(dev);
+ /* set us as active - note we won't do PM ops until cc_trng_pm_go()! */
+ return pm_runtime_set_active(dev);
+}
+
+static void cc_trng_pm_go(struct cctrng_drvdata *drvdata)
+{
+ struct device *dev = &(drvdata->pdev->dev);
+
+ /* enable the PM module*/
+ pm_runtime_enable(dev);
+}
+
+static void cc_trng_pm_fini(struct cctrng_drvdata *drvdata)
+{
+ struct device *dev = &(drvdata->pdev->dev);
+
+ pm_runtime_disable(dev);
+}
+
+
+static inline int cc_trng_parse_sampling_ratio(struct cctrng_drvdata *drvdata)
+{
+ struct device *dev = &(drvdata->pdev->dev);
+ struct device_node *np = drvdata->pdev->dev.of_node;
+ int rc;
+ int i;
+ /* ret will be set to 0 if at least one rosc has (sampling ratio > 0) */
+ int ret = -EINVAL;
+
+ rc = of_property_read_u32_array(np, "arm,rosc-ratio",
+ drvdata->smpl_ratio,
+ CC_TRNG_NUM_OF_ROSCS);
+ if (rc) {
+ /* arm,rosc-ratio was not found in device tree */
+ return rc;
+ }
+
+ /* verify that at least one rosc has (sampling ratio > 0) */
+ for (i = 0; i < CC_TRNG_NUM_OF_ROSCS; ++i) {
+ dev_dbg(dev, "rosc %d sampling ratio %u",
+ i, drvdata->smpl_ratio[i]);
+
+ if (drvdata->smpl_ratio[i] > 0)
+ ret = 0;
+ }
+
+ return ret;
+}
+
+static int cc_trng_change_rosc(struct cctrng_drvdata *drvdata)
+{
+ struct device *dev = &(drvdata->pdev->dev);
+
+ dev_dbg(dev, "cctrng change rosc (was %d)\n", drvdata->active_rosc);
+ drvdata->active_rosc += 1;
+
+ while (drvdata->active_rosc < CC_TRNG_NUM_OF_ROSCS) {
+ if (drvdata->smpl_ratio[drvdata->active_rosc] > 0)
+ return 0;
+
+ drvdata->active_rosc += 1;
+ }
+ return -EINVAL;
+}
+
+
+static void cc_trng_enable_rnd_source(struct cctrng_drvdata *drvdata)
+{
+ u32 max_cycles;
+
+ /* Set watchdog threshold to maximal allowed time (in CPU cycles) */
+ max_cycles = CCTRNG_TIMEOUT(drvdata->smpl_ratio[drvdata->active_rosc]);
+ cc_iowrite(drvdata, CC_RNG_WATCHDOG_VAL_REG_OFFSET, max_cycles);
+
+ /* enable the RND source */
+ cc_iowrite(drvdata, CC_RND_SOURCE_ENABLE_REG_OFFSET, 0x1);
+
+ /* unmask RNG interrupts */
+ cc_iowrite(drvdata, CC_RNG_IMR_REG_OFFSET, (u32)~CC_RNG_INT_MASK);
+}
+
+
+/* increase circular data buffer index (head/tail) */
+static inline void circ_idx_inc(int *idx, int bytes)
+{
+ *idx += (bytes + 3) >> 2;
+ *idx &= (CCTRNG_DATA_BUF_WORDS - 1);
+}
+
+static inline size_t circ_buf_space(struct cctrng_drvdata *drvdata)
+{
+ return CIRC_SPACE(drvdata->circ.head,
+ drvdata->circ.tail, CCTRNG_DATA_BUF_WORDS);
+
+}
+
+static int cctrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ /* current implementation ignores "wait" */
+
+ struct cctrng_drvdata *drvdata = (struct cctrng_drvdata *)rng->priv;
+ struct device *dev = &(drvdata->pdev->dev);
+ u32 *buf = (u32 *)drvdata->circ.buf;
+ size_t copied = 0;
+ size_t cnt_w;
+ size_t size;
+ size_t left;
+
+ if (!spin_trylock(&drvdata->read_lock)) {
+ /* concurrent consumers from data_buf cannot be served */
+ dev_dbg_ratelimited(dev, "unable to hold lock\n");
+ return 0;
+ }
+
+ /* copy till end of data buffer (without wrap back) */
+ cnt_w = CIRC_CNT_TO_END(drvdata->circ.head,
+ drvdata->circ.tail, CCTRNG_DATA_BUF_WORDS);
+ size = min((cnt_w<<2), max);
+ memcpy(data, &(buf[drvdata->circ.tail]), size);
+ copied = size;
+ circ_idx_inc(&drvdata->circ.tail, size);
+ /* copy rest of data in data buffer */
+ left = max - copied;
+ if (left > 0) {
+ cnt_w = CIRC_CNT(drvdata->circ.head,
+ drvdata->circ.tail, CCTRNG_DATA_BUF_WORDS);
+ size = min((cnt_w<<2), left);
+ memcpy(data, &(buf[drvdata->circ.tail]), size);
+ copied += size;
+ circ_idx_inc(&drvdata->circ.tail, size);
+ }
+
+ spin_unlock(&drvdata->read_lock);
+
+ if (circ_buf_space(drvdata) >= CC_TRNG_EHR_IN_WORDS) {
+ if (atomic_cmpxchg(&drvdata->pending_hw, 0, 1) == 0) {
+ /* re-check space in buffer to avoid potential race */
+ if (circ_buf_space(drvdata) >= CC_TRNG_EHR_IN_WORDS) {
+ /* increment device's usage counter */
+ int rc = cc_trng_pm_get(dev);
+
+ if (rc) {
+ dev_err(dev,
+ "cc_trng_pm_get returned %x\n",
+ rc);
+ return rc;
+ }
+
+ /* schedule execution of deferred work handler
+ * for filling of data buffer
+ */
+ schedule_work(&drvdata->startwork);
+ } else {
+ atomic_set(&drvdata->pending_hw, 0);
+ }
+ }
+ }
+
+ return copied;
+}
+
+static void cc_trng_hw_trigger(struct cctrng_drvdata *drvdata)
+{
+ u32 tmp_smpl_cnt = 0;
+ struct device *dev = &(drvdata->pdev->dev);
+
+ dev_dbg(dev, "cctrng hw trigger.\n");
+
+ /* enable the HW RND clock */
+ cc_iowrite(drvdata, CC_RNG_CLK_ENABLE_REG_OFFSET, 0x1);
+
+ /* do software reset */
+ cc_iowrite(drvdata, CC_RNG_SW_RESET_REG_OFFSET, 0x1);
+ /* in order to verify that the reset has completed,
+ * the sample count need to be verified
+ */
+ do {
+ /* enable the HW RND clock */
+ cc_iowrite(drvdata, CC_RNG_CLK_ENABLE_REG_OFFSET, 0x1);
+
+ /* set sampling ratio (rng_clocks) between consecutive bits */
+ cc_iowrite(drvdata, CC_SAMPLE_CNT1_REG_OFFSET,
+ drvdata->smpl_ratio[drvdata->active_rosc]);
+
+ /* read the sampling ratio */
+ tmp_smpl_cnt = cc_ioread(drvdata, CC_SAMPLE_CNT1_REG_OFFSET);
+
+ } while (tmp_smpl_cnt != drvdata->smpl_ratio[drvdata->active_rosc]);
+
+ /* disable the RND source for setting new parameters in HW */
+ cc_iowrite(drvdata, CC_RND_SOURCE_ENABLE_REG_OFFSET, 0);
+
+ cc_iowrite(drvdata, CC_RNG_ICR_REG_OFFSET, 0xFFFFFFFF);
+
+ cc_iowrite(drvdata, CC_TRNG_CONFIG_REG_OFFSET, drvdata->active_rosc);
+
+ /* Debug Control register: set to 0 - no bypasses */
+ cc_iowrite(drvdata, CC_TRNG_DEBUG_CONTROL_REG_OFFSET, 0);
+
+ cc_trng_enable_rnd_source(drvdata);
+}
+
+void cc_trng_compwork_handler(struct work_struct *w)
+{
+ u32 isr = 0;
+ u32 ehr_valid = 0;
+ struct cctrng_drvdata *drvdata =
+ container_of(w, struct cctrng_drvdata, compwork);
+ struct device *dev = &(drvdata->pdev->dev);
+ int i;
+
+ /* stop DMA and the RNG source */
+ cc_iowrite(drvdata, CC_RNG_DMA_ENABLE_REG_OFFSET, 0);
+ cc_iowrite(drvdata, CC_RND_SOURCE_ENABLE_REG_OFFSET, 0);
+
+ /* read RNG_ISR and check for errors */
+ isr = cc_ioread(drvdata, CC_RNG_ISR_REG_OFFSET);
+ ehr_valid = CC_REG_FLD_GET(RNG_ISR, EHR_VALID, isr);
+ dev_dbg(dev, "Got RNG_ISR=0x%08X (EHR_VALID=%u)\n", isr, ehr_valid);
+
+#ifdef CONFIG_CRYPTO_FIPS
+ if (CC_REG_FLD_GET(RNG_ISR, CRNGT_ERR, isr) && fips_enabled) {
+ fips_fail_notify();
+ /* FIPS error is fatal */
+ panic("Got HW CRNGT error while fips is enabled!\n");
+ }
+#endif
+
+ /* Clear all pending RNG interrupts */
+ cc_iowrite(drvdata, CC_RNG_ICR_REG_OFFSET, isr);
+
+
+ if (!ehr_valid) {
+ /* in case of AUTOCORR/TIMEOUT error, try the next ROSC */
+ if (CC_REG_FLD_GET(RNG_ISR, AUTOCORR_ERR, isr) ||
+ CC_REG_FLD_GET(RNG_ISR, WATCHDOG, isr)) {
+ dev_dbg(dev, "cctrng autocorr/timeout error.\n");
+ goto next_rosc;
+ }
+
+ /* in case of VN error, ignore it */
+ }
+
+ /* read EHR data from registers */
+ for (i = 0; i < CC_TRNG_EHR_IN_WORDS; i++) {
+ /* calc word ptr in data_buf */
+ u32 *buf = (u32 *)drvdata->circ.buf;
+
+ buf[drvdata->circ.head] = cc_ioread(drvdata,
+ CC_EHR_DATA_0_REG_OFFSET + (i*sizeof(u32)));
+
+ /* EHR_DATA registers are cleared on read. In case 0 value was
+ * returned, restart the entropy collection.
+ */
+ if (buf[drvdata->circ.head] == 0) {
+ dev_dbg(dev, "Got 0 value in EHR. active_rosc %u\n",
+ drvdata->active_rosc);
+ goto next_rosc;
+ }
+
+ circ_idx_inc(&drvdata->circ.head, 1<<2);
+ }
+
+ atomic_set(&drvdata->pending_hw, 0);
+
+ /* continue to fill data buffer if needed */
+ if (circ_buf_space(drvdata) >= CC_TRNG_EHR_IN_WORDS) {
+ if (atomic_cmpxchg(&drvdata->pending_hw, 0, 1) == 0) {
+ /* Re-enable rnd source */
+ cc_trng_enable_rnd_source(drvdata);
+ return;
+ }
+ }
+
+ cc_trng_pm_put_suspend(dev);
+
+ dev_dbg(dev, "compwork handler done\n");
+ return;
+
+next_rosc:
+ if ((circ_buf_space(drvdata) >= CC_TRNG_EHR_IN_WORDS) &&
+ (cc_trng_change_rosc(drvdata) == 0)) {
+ /* trigger trng hw with next rosc */
+ cc_trng_hw_trigger(drvdata);
+ } else {
+ atomic_set(&drvdata->pending_hw, 0);
+ cc_trng_pm_put_suspend(dev);
+ }
+}
+
+static irqreturn_t cc_isr(int irq, void *dev_id)
+{
+ struct cctrng_drvdata *drvdata = (struct cctrng_drvdata *)dev_id;
+ struct device *dev = &(drvdata->pdev->dev);
+ u32 irr;
+
+ /* if driver suspended return, probably shared interrupt */
+ if (pm_runtime_suspended(dev))
+ return IRQ_NONE;
+
+ /* read the interrupt status */
+ irr = cc_ioread(drvdata, CC_HOST_RGF_IRR_REG_OFFSET);
+ dev_dbg(dev, "Got IRR=0x%08X\n", irr);
+
+ if (irr == 0) /* Probably shared interrupt line */
+ return IRQ_NONE;
+
+ /* clear interrupt - must be before processing events */
+ cc_iowrite(drvdata, CC_HOST_RGF_ICR_REG_OFFSET, irr);
+
+ /* RNG interrupt - most probable */
+ if (irr & CC_HOST_RNG_IRQ_MASK) {
+ /* Mask RNG interrupts - will be unmasked in deferred work */
+ cc_iowrite(drvdata, CC_RNG_IMR_REG_OFFSET, 0xFFFFFFFF);
+
+ /* We clear RNG interrupt here,
+ * to avoid it from firing as we'll unmask RNG interrupts.
+ */
+ cc_iowrite(drvdata, CC_HOST_RGF_ICR_REG_OFFSET,
+ CC_HOST_RNG_IRQ_MASK);
+
+ irr &= ~CC_HOST_RNG_IRQ_MASK;
+
+ /* schedule execution of deferred work handler */
+ schedule_work(&drvdata->compwork);
+ }
+
+ if (irr) {
+ dev_dbg_ratelimited(dev,
+ "IRR includes unknown cause bits (0x%08X)\n",
+ irr);
+ /* Just warning */
+ }
+
+ return IRQ_HANDLED;
+}
+
+void cc_trng_startwork_handler(struct work_struct *w)
+{
+ struct cctrng_drvdata *drvdata =
+ container_of(w, struct cctrng_drvdata, startwork);
+
+ drvdata->active_rosc = 0;
+ cc_trng_hw_trigger(drvdata);
+}
+
+
+static int cc_trng_clk_init(struct cctrng_drvdata *drvdata)
+{
+ struct clk *clk;
+ struct device *dev = &(drvdata->pdev->dev);
+ int rc = 0;
+
+ clk = devm_clk_get_optional(dev, NULL);
+ if (IS_ERR(clk)) {
+ if (PTR_ERR(clk) != -EPROBE_DEFER)
+ dev_err(dev, "Error getting clock: %pe\n", clk);
+ return PTR_ERR(clk);
+ }
+ drvdata->clk = clk;
+
+ rc = clk_prepare_enable(drvdata->clk);
+ if (rc) {
+ dev_err(dev, "Failed to enable clock\n");
+ return rc;
+ }
+
+ return 0;
+}
+
+static void cc_trng_clk_fini(struct cctrng_drvdata *drvdata)
+{
+ clk_disable_unprepare(drvdata->clk);
+}
+
+
+static int cctrng_probe(struct platform_device *pdev)
+{
+ struct resource *req_mem_cc_regs = NULL;
+ struct cctrng_drvdata *drvdata;
+ struct device *dev = &pdev->dev;
+ int rc = 0;
+ u32 val;
+ int irq;
+
+ drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+ if (!drvdata)
+ return -ENOMEM;
+
+ drvdata->rng.name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
+ if (!drvdata->rng.name)
+ return -ENOMEM;
+
+ drvdata->rng.read = cctrng_read;
+ drvdata->rng.priv = (unsigned long)drvdata;
+ drvdata->rng.quality = CC_TRNG_QUALITY;
+
+ platform_set_drvdata(pdev, drvdata);
+ drvdata->pdev = pdev;
+
+ drvdata->circ.buf = (char *)drvdata->data_buf;
+
+ /* Get device resources */
+ /* First CC registers space */
+ req_mem_cc_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ /* Map registers space */
+ drvdata->cc_base = devm_ioremap_resource(dev, req_mem_cc_regs);
+ if (IS_ERR(drvdata->cc_base)) {
+ dev_err(dev, "Failed to ioremap registers");
+ return PTR_ERR(drvdata->cc_base);
+ }
+
+ dev_dbg(dev, "Got MEM resource (%s): %pR\n", req_mem_cc_regs->name,
+ req_mem_cc_regs);
+ dev_dbg(dev, "CC registers mapped from %pa to 0x%p\n",
+ &req_mem_cc_regs->start, drvdata->cc_base);
+
+ /* Then IRQ */
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(dev, "Failed getting IRQ resource\n");
+ return irq;
+ }
+
+ /* parse sampling rate from device tree */
+ rc = cc_trng_parse_sampling_ratio(drvdata);
+ if (rc) {
+ dev_err(dev, "Failed to get legal sampling ratio for rosc\n");
+ return rc;
+ }
+
+ rc = cc_trng_clk_init(drvdata);
+ if (rc) {
+ dev_err(dev, "cc_trng_clk_init failed\n");
+ return rc;
+ }
+
+ INIT_WORK(&drvdata->compwork, cc_trng_compwork_handler);
+ INIT_WORK(&drvdata->startwork, cc_trng_startwork_handler);
+ spin_lock_init(&drvdata->read_lock);
+
+ /* register the driver isr function */
+ rc = devm_request_irq(dev, irq, cc_isr, IRQF_SHARED, "cctrng", drvdata);
+ if (rc) {
+ dev_err(dev, "Could not register to interrupt %d\n", irq);
+ goto post_clk_err;
+ }
+ dev_dbg(dev, "Registered to IRQ: %d\n", irq);
+
+ /* Clear all pending interrupts */
+ val = cc_ioread(drvdata, CC_HOST_RGF_IRR_REG_OFFSET);
+ dev_dbg(dev, "IRR=0x%08X\n", val);
+ cc_iowrite(drvdata, CC_HOST_RGF_ICR_REG_OFFSET, val);
+
+ /* unmask HOST RNG interrupt */
+ cc_iowrite(drvdata, CC_HOST_RGF_IMR_REG_OFFSET,
+ cc_ioread(drvdata, CC_HOST_RGF_IMR_REG_OFFSET) &
+ ~CC_HOST_RNG_IRQ_MASK);
+
+ /* init PM */
+ rc = cc_trng_pm_init(drvdata);
+ if (rc) {
+ dev_err(dev, "cc_trng_pm_init failed\n");
+ goto post_clk_err;
+ }
+
+ /* increment device's usage counter */
+ rc = cc_trng_pm_get(dev);
+ if (rc) {
+ dev_err(dev, "cc_trng_pm_get returned %x\n", rc);
+ goto post_pm_err;
+ }
+
+ /* set pending_hw to verify that HW won't be triggered from read */
+ atomic_set(&drvdata->pending_hw, 1);
+
+ /* registration of the hwrng device */
+ rc = hwrng_register(&drvdata->rng);
+ if (rc) {
+ dev_err(dev, "Could not register hwrng device.\n");
+ goto post_pm_err;
+ }
+
+ /* trigger HW to start generate data */
+ drvdata->active_rosc = 0;
+ cc_trng_hw_trigger(drvdata);
+
+ /* All set, we can allow auto-suspend */
+ cc_trng_pm_go(drvdata);
+
+ dev_info(dev, "ARM cctrng device initialized\n");
+
+ return 0;
+
+post_pm_err:
+ cc_trng_pm_fini(drvdata);
+
+post_clk_err:
+ cc_trng_clk_fini(drvdata);
+
+ return rc;
+}
+
+static int cctrng_remove(struct platform_device *pdev)
+{
+ struct cctrng_drvdata *drvdata = platform_get_drvdata(pdev);
+ struct device *dev = &pdev->dev;
+
+ dev_dbg(dev, "Releasing cctrng resources...\n");
+
+ hwrng_unregister(&drvdata->rng);
+
+ cc_trng_pm_fini(drvdata);
+
+ cc_trng_clk_fini(drvdata);
+
+ dev_info(dev, "ARM cctrng device terminated\n");
+
+ return 0;
+}
+
+static int __maybe_unused cctrng_suspend(struct device *dev)
+{
+ struct cctrng_drvdata *drvdata = dev_get_drvdata(dev);
+
+ dev_dbg(dev, "set HOST_POWER_DOWN_EN\n");
+ cc_iowrite(drvdata, CC_HOST_POWER_DOWN_EN_REG_OFFSET,
+ POWER_DOWN_ENABLE);
+
+ clk_disable_unprepare(drvdata->clk);
+
+ return 0;
+}
+
+static bool cctrng_wait_for_reset_completion(struct cctrng_drvdata *drvdata)
+{
+ unsigned int val;
+ unsigned int i;
+
+ for (i = 0; i < CC_HW_RESET_LOOP_COUNT; i++) {
+ /* in cc7x3 NVM_IS_IDLE indicates that CC reset is
+ * completed and device is fully functional
+ */
+ val = cc_ioread(drvdata, CC_NVM_IS_IDLE_REG_OFFSET);
+ if (val & BIT(CC_NVM_IS_IDLE_VALUE_BIT_SHIFT)) {
+ /* hw indicate reset completed */
+ return true;
+ }
+ /* allow scheduling other process on the processor */
+ schedule();
+ }
+ /* reset not completed */
+ return false;
+}
+
+static int __maybe_unused cctrng_resume(struct device *dev)
+{
+ struct cctrng_drvdata *drvdata = dev_get_drvdata(dev);
+ int rc;
+
+ dev_dbg(dev, "unset HOST_POWER_DOWN_EN\n");
+ /* Enables the device source clk */
+ rc = clk_prepare_enable(drvdata->clk);
+ if (rc) {
+ dev_err(dev, "failed getting clock back on. We're toast.\n");
+ return rc;
+ }
+
+ /* wait for Cryptocell reset completion */
+ if (!cctrng_wait_for_reset_completion(drvdata)) {
+ dev_err(dev, "Cryptocell reset not completed");
+ return -EBUSY;
+ }
+
+ /* unmask HOST RNG interrupt */
+ cc_iowrite(drvdata, CC_HOST_RGF_IMR_REG_OFFSET,
+ cc_ioread(drvdata, CC_HOST_RGF_IMR_REG_OFFSET) &
+ ~CC_HOST_RNG_IRQ_MASK);
+
+ cc_iowrite(drvdata, CC_HOST_POWER_DOWN_EN_REG_OFFSET,
+ POWER_DOWN_DISABLE);
+
+ return 0;
+}
+
+static UNIVERSAL_DEV_PM_OPS(cctrng_pm, cctrng_suspend, cctrng_resume, NULL);
+
+static const struct of_device_id arm_cctrng_dt_match[] = {
+ { .compatible = "arm,cryptocell-713-trng", },
+ { .compatible = "arm,cryptocell-703-trng", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, arm_cctrng_dt_match);
+
+static struct platform_driver cctrng_driver = {
+ .driver = {
+ .name = "cctrng",
+ .of_match_table = arm_cctrng_dt_match,
+ .pm = &cctrng_pm,
+ },
+ .probe = cctrng_probe,
+ .remove = cctrng_remove,
+};
+
+static int __init cctrng_mod_init(void)
+{
+ /* Compile time assertion checks */
+ BUILD_BUG_ON(CCTRNG_DATA_BUF_WORDS < 6);
+ BUILD_BUG_ON((CCTRNG_DATA_BUF_WORDS & (CCTRNG_DATA_BUF_WORDS-1)) != 0);
+
+ return platform_driver_register(&cctrng_driver);
+}
+module_init(cctrng_mod_init);
+
+static void __exit cctrng_mod_exit(void)
+{
+ platform_driver_unregister(&cctrng_driver);
+}
+module_exit(cctrng_mod_exit);
+
+/* Module description */
+MODULE_DESCRIPTION("ARM CryptoCell TRNG Driver");
+MODULE_AUTHOR("ARM");
+MODULE_LICENSE("GPL v2");
projects / platform / kernel / linux-rpi.git / commitdiff