crypto: ccp - add TEE support for Raven Ridge

Adds a PCI device entry for Raven Ridge. Raven Ridge is an APU with a
dedicated AMD Secure Processor having Trusted Execution Environment (TEE)
support. The TEE provides a secure environment for running Trusted
Applications (TAs) which implement security-sensitive parts of a feature.

This patch configures AMD Secure Processor's TEE interface by initializing
a ring buffer (shared memory between Rich OS and Trusted OS) which can hold
multiple command buffer entries. The TEE interface is facilitated by a set
of CPU to PSP mailbox registers.

The next patch will address how commands are submitted to the ring buffer.

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Co-developed-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Acked-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 238 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/tee-dev.c b/drivers/crypto/ccp/tee-dev.c
new file mode 100644
index 000000000000..ccbc2ce59d51
--- /dev/null
+++ b/drivers/crypto/ccp/tee-dev.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: MIT
+/*
+ * AMD Trusted Execution Environment (TEE) interface
+ *
+ * Author: Rijo Thomas <Rijo-john.Thomas@amd.com>
+ * Author: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
+ *
+ * Copyright 2019 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/gfp.h>
+#include <linux/psp-sev.h>
+
+#include "psp-dev.h"
+#include "tee-dev.h"
+
+static bool psp_dead;
+
+static int tee_alloc_ring(struct psp_tee_device *tee, int ring_size)
+{
+	struct ring_buf_manager *rb_mgr = &tee->rb_mgr;
+	void *start_addr;
+
+	if (!ring_size)
+		return -EINVAL;
+
+	/* We need actual physical address instead of DMA address, since
+	 * Trusted OS running on AMD Secure Processor will map this region
+	 */
+	start_addr = (void *)__get_free_pages(GFP_KERNEL, get_order(ring_size));
+	if (!start_addr)
+		return -ENOMEM;
+
+	rb_mgr->ring_start = start_addr;
+	rb_mgr->ring_size = ring_size;
+	rb_mgr->ring_pa = __psp_pa(start_addr);
+
+	return 0;
+}
+
+static void tee_free_ring(struct psp_tee_device *tee)
+{
+	struct ring_buf_manager *rb_mgr = &tee->rb_mgr;
+
+	if (!rb_mgr->ring_start)
+		return;
+
+	free_pages((unsigned long)rb_mgr->ring_start,
+		   get_order(rb_mgr->ring_size));
+
+	rb_mgr->ring_start = NULL;
+	rb_mgr->ring_size = 0;
+	rb_mgr->ring_pa = 0;
+}
+
+static int tee_wait_cmd_poll(struct psp_tee_device *tee, unsigned int timeout,
+			     unsigned int *reg)
+{
+	/* ~10ms sleep per loop => nloop = timeout * 100 */
+	int nloop = timeout * 100;
+
+	while (--nloop) {
+		*reg = ioread32(tee->io_regs + tee->vdata->cmdresp_reg);
+		if (*reg & PSP_CMDRESP_RESP)
+			return 0;
+
+		usleep_range(10000, 10100);
+	}
+
+	dev_err(tee->dev, "tee: command timed out, disabling PSP\n");
+	psp_dead = true;
+
+	return -ETIMEDOUT;
+}
+
+static
+struct tee_init_ring_cmd *tee_alloc_cmd_buffer(struct psp_tee_device *tee)
+{
+	struct tee_init_ring_cmd *cmd;
+
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return NULL;
+
+	cmd->hi_addr = upper_32_bits(tee->rb_mgr.ring_pa);
+	cmd->low_addr = lower_32_bits(tee->rb_mgr.ring_pa);
+	cmd->size = tee->rb_mgr.ring_size;
+
+	dev_dbg(tee->dev, "tee: ring address: high = 0x%x low = 0x%x size = %u\n",
+		cmd->hi_addr, cmd->low_addr, cmd->size);
+
+	return cmd;
+}
+
+static inline void tee_free_cmd_buffer(struct tee_init_ring_cmd *cmd)
+{
+	kfree(cmd);
+}
+
+static int tee_init_ring(struct psp_tee_device *tee)
+{
+	int ring_size = MAX_RING_BUFFER_ENTRIES * sizeof(struct tee_ring_cmd);
+	struct tee_init_ring_cmd *cmd;
+	phys_addr_t cmd_buffer;
+	unsigned int reg;
+	int ret;
+
+	BUILD_BUG_ON(sizeof(struct tee_ring_cmd) != 1024);
+
+	ret = tee_alloc_ring(tee, ring_size);
+	if (ret) {
+		dev_err(tee->dev, "tee: ring allocation failed %d\n", ret);
+		return ret;
+	}
+
+	tee->rb_mgr.wptr = 0;
+
+	cmd = tee_alloc_cmd_buffer(tee);
+	if (!cmd) {
+		tee_free_ring(tee);
+		return -ENOMEM;
+	}
+
+	cmd_buffer = __psp_pa((void *)cmd);
+
+	/* Send command buffer details to Trusted OS by writing to
+	 * CPU-PSP message registers
+	 */
+
+	iowrite32(lower_32_bits(cmd_buffer),
+		  tee->io_regs + tee->vdata->cmdbuff_addr_lo_reg);
+	iowrite32(upper_32_bits(cmd_buffer),
+		  tee->io_regs + tee->vdata->cmdbuff_addr_hi_reg);
+	iowrite32(TEE_RING_INIT_CMD,
+		  tee->io_regs + tee->vdata->cmdresp_reg);
+
+	ret = tee_wait_cmd_poll(tee, TEE_DEFAULT_TIMEOUT, &reg);
+	if (ret) {
+		dev_err(tee->dev, "tee: ring init command timed out\n");
+		tee_free_ring(tee);
+		goto free_buf;
+	}
+
+	if (reg & PSP_CMDRESP_ERR_MASK) {
+		dev_err(tee->dev, "tee: ring init command failed (%#010x)\n",
+			reg & PSP_CMDRESP_ERR_MASK);
+		tee_free_ring(tee);
+		ret = -EIO;
+	}
+
+free_buf:
+	tee_free_cmd_buffer(cmd);
+
+	return ret;
+}
+
+static void tee_destroy_ring(struct psp_tee_device *tee)
+{
+	unsigned int reg;
+	int ret;
+
+	if (!tee->rb_mgr.ring_start)
+		return;
+
+	if (psp_dead)
+		goto free_ring;
+
+	iowrite32(TEE_RING_DESTROY_CMD,
+		  tee->io_regs + tee->vdata->cmdresp_reg);
+
+	ret = tee_wait_cmd_poll(tee, TEE_DEFAULT_TIMEOUT, &reg);
+	if (ret) {
+		dev_err(tee->dev, "tee: ring destroy command timed out\n");
+	} else if (reg & PSP_CMDRESP_ERR_MASK) {
+		dev_err(tee->dev, "tee: ring destroy command failed (%#010x)\n",
+			reg & PSP_CMDRESP_ERR_MASK);
+	}
+
+free_ring:
+	tee_free_ring(tee);
+}
+
+int tee_dev_init(struct psp_device *psp)
+{
+	struct device *dev = psp->dev;
+	struct psp_tee_device *tee;
+	int ret;
+
+	ret = -ENOMEM;
+	tee = devm_kzalloc(dev, sizeof(*tee), GFP_KERNEL);
+	if (!tee)
+		goto e_err;
+
+	psp->tee_data = tee;
+
+	tee->dev = dev;
+	tee->psp = psp;
+
+	tee->io_regs = psp->io_regs;
+
+	tee->vdata = (struct tee_vdata *)psp->vdata->tee;
+	if (!tee->vdata) {
+		ret = -ENODEV;
+		dev_err(dev, "tee: missing driver data\n");
+		goto e_err;
+	}
+
+	ret = tee_init_ring(tee);
+	if (ret) {
+		dev_err(dev, "tee: failed to init ring buffer\n");
+		goto e_err;
+	}
+
+	dev_notice(dev, "tee enabled\n");
+
+	return 0;
+
+e_err:
+	psp->tee_data = NULL;
+
+	dev_notice(dev, "tee initialization failed\n");
+
+	return ret;
+}
+
+void tee_dev_destroy(struct psp_device *psp)
+{
+	struct psp_tee_device *tee = psp->tee_data;
+
+	if (!tee)
+		return;
+
+	tee_destroy_ring(tee);
+}