#include <linux/errno.h>
#include <linux/err.h>
#include <linux/interrupt.h>
+#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/spi/pxa2xx_spi.h>
#include <linux/spi/spi.h>
#include <linux/pm_runtime.h>
#include <linux/acpi.h>
-#include <asm/io.h>
-#include <asm/irq.h>
-#include <asm/delay.h>
-
#include "spi-pxa2xx.h"
MODULE_AUTHOR("Stephen Street");
| QUARK_X1000_SSCR1_TFT \
| SSCR1_SPH | SSCR1_SPO | SSCR1_LBM)
-#define LPSS_RX_THRESH_DFLT 64
-#define LPSS_TX_LOTHRESH_DFLT 160
-#define LPSS_TX_HITHRESH_DFLT 224
+#define GENERAL_REG_RXTO_HOLDOFF_DISABLE BIT(24)
+#define SPI_CS_CONTROL_SW_MODE BIT(0)
+#define SPI_CS_CONTROL_CS_HIGH BIT(1)
-struct quark_spi_rate {
- u32 bitrate;
- u32 dds_clk_rate;
- u32 clk_div;
+struct lpss_config {
+ /* LPSS offset from drv_data->ioaddr */
+ unsigned offset;
+ /* Register offsets from drv_data->lpss_base or -1 */
+ int reg_general;
+ int reg_ssp;
+ int reg_cs_ctrl;
+ /* FIFO thresholds */
+ u32 rx_threshold;
+ u32 tx_threshold_lo;
+ u32 tx_threshold_hi;
};
-/*
- * 'rate', 'dds', 'clk_div' lookup table, which is defined in
- * the Quark SPI datasheet.
- */
-static const struct quark_spi_rate quark_spi_rate_table[] = {
-/* bitrate, dds_clk_rate, clk_div */
- {50000000, 0x800000, 0},
- {40000000, 0x666666, 0},
- {25000000, 0x400000, 0},
- {20000000, 0x666666, 1},
- {16667000, 0x800000, 2},
- {13333000, 0x666666, 2},
- {12500000, 0x200000, 0},
- {10000000, 0x800000, 4},
- {8000000, 0x666666, 4},
- {6250000, 0x400000, 3},
- {5000000, 0x400000, 4},
- {4000000, 0x666666, 9},
- {3125000, 0x80000, 0},
- {2500000, 0x400000, 9},
- {2000000, 0x666666, 19},
- {1563000, 0x40000, 0},
- {1250000, 0x200000, 9},
- {1000000, 0x400000, 24},
- {800000, 0x666666, 49},
- {781250, 0x20000, 0},
- {625000, 0x200000, 19},
- {500000, 0x400000, 49},
- {400000, 0x666666, 99},
- {390625, 0x10000, 0},
- {250000, 0x400000, 99},
- {200000, 0x666666, 199},
- {195313, 0x8000, 0},
- {125000, 0x100000, 49},
- {100000, 0x200000, 124},
- {50000, 0x100000, 124},
- {25000, 0x80000, 124},
- {10016, 0x20000, 77},
- {5040, 0x20000, 154},
- {1002, 0x8000, 194},
+/* Keep these sorted with enum pxa_ssp_type */
+static const struct lpss_config lpss_platforms[] = {
+ { /* LPSS_LPT_SSP */
+ .offset = 0x800,
+ .reg_general = 0x08,
+ .reg_ssp = 0x0c,
+ .reg_cs_ctrl = 0x18,
+ .rx_threshold = 64,
+ .tx_threshold_lo = 160,
+ .tx_threshold_hi = 224,
+ },
+ { /* LPSS_BYT_SSP */
+ .offset = 0x400,
+ .reg_general = 0x08,
+ .reg_ssp = 0x0c,
+ .reg_cs_ctrl = 0x18,
+ .rx_threshold = 64,
+ .tx_threshold_lo = 160,
+ .tx_threshold_hi = 224,
+ },
};
-/* Offset from drv_data->lpss_base */
-#define GENERAL_REG 0x08
-#define GENERAL_REG_RXTO_HOLDOFF_DISABLE BIT(24)
-#define SSP_REG 0x0c
-#define SPI_CS_CONTROL 0x18
-#define SPI_CS_CONTROL_SW_MODE BIT(0)
-#define SPI_CS_CONTROL_CS_HIGH BIT(1)
+static inline const struct lpss_config
+*lpss_get_config(const struct driver_data *drv_data)
+{
+ return &lpss_platforms[drv_data->ssp_type - LPSS_LPT_SSP];
+}
static bool is_lpss_ssp(const struct driver_data *drv_data)
{
- return drv_data->ssp_type == LPSS_SSP;
+ switch (drv_data->ssp_type) {
+ case LPSS_LPT_SSP:
+ case LPSS_BYT_SSP:
+ return true;
+ default:
+ return false;
+ }
}
static bool is_quark_x1000_ssp(const struct driver_data *drv_data)
*/
static void lpss_ssp_setup(struct driver_data *drv_data)
{
- unsigned offset = 0x400;
- u32 value, orig;
-
- /*
- * Perform auto-detection of the LPSS SSP private registers. They
- * can be either at 1k or 2k offset from the base address.
- */
- orig = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-
- /* Test SPI_CS_CONTROL_SW_MODE bit enabling */
- value = orig | SPI_CS_CONTROL_SW_MODE;
- writel(value, drv_data->ioaddr + offset + SPI_CS_CONTROL);
- value = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
- if (value != (orig | SPI_CS_CONTROL_SW_MODE)) {
- offset = 0x800;
- goto detection_done;
- }
-
- orig = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-
- /* Test SPI_CS_CONTROL_SW_MODE bit disabling */
- value = orig & ~SPI_CS_CONTROL_SW_MODE;
- writel(value, drv_data->ioaddr + offset + SPI_CS_CONTROL);
- value = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
- if (value != (orig & ~SPI_CS_CONTROL_SW_MODE)) {
- offset = 0x800;
- goto detection_done;
- }
+ const struct lpss_config *config;
+ u32 value;
-detection_done:
- /* Now set the LPSS base */
- drv_data->lpss_base = drv_data->ioaddr + offset;
+ config = lpss_get_config(drv_data);
+ drv_data->lpss_base = drv_data->ioaddr + config->offset;
/* Enable software chip select control */
value = SPI_CS_CONTROL_SW_MODE | SPI_CS_CONTROL_CS_HIGH;
- __lpss_ssp_write_priv(drv_data, SPI_CS_CONTROL, value);
+ __lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value);
/* Enable multiblock DMA transfers */
if (drv_data->master_info->enable_dma) {
- __lpss_ssp_write_priv(drv_data, SSP_REG, 1);
-
- value = __lpss_ssp_read_priv(drv_data, GENERAL_REG);
- value |= GENERAL_REG_RXTO_HOLDOFF_DISABLE;
- __lpss_ssp_write_priv(drv_data, GENERAL_REG, value);
+ __lpss_ssp_write_priv(drv_data, config->reg_ssp, 1);
+
+ if (config->reg_general >= 0) {
+ value = __lpss_ssp_read_priv(drv_data,
+ config->reg_general);
+ value |= GENERAL_REG_RXTO_HOLDOFF_DISABLE;
+ __lpss_ssp_write_priv(drv_data,
+ config->reg_general, value);
+ }
}
}
static void lpss_ssp_cs_control(struct driver_data *drv_data, bool enable)
{
+ const struct lpss_config *config;
u32 value;
- value = __lpss_ssp_read_priv(drv_data, SPI_CS_CONTROL);
+ config = lpss_get_config(drv_data);
+
+ value = __lpss_ssp_read_priv(drv_data, config->reg_cs_ctrl);
if (enable)
value &= ~SPI_CS_CONTROL_CS_HIGH;
else
value |= SPI_CS_CONTROL_CS_HIGH;
- __lpss_ssp_write_priv(drv_data, SPI_CS_CONTROL, value);
+ __lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value);
}
static void cs_assert(struct driver_data *drv_data)
}
/*
- * The Quark SPI data sheet gives a table, and for the given 'rate',
- * the 'dds' and 'clk_div' can be found in the table.
+ * The Quark SPI has an additional 24 bit register (DDS_CLK_RATE) to multiply
+ * input frequency by fractions of 2^24. It also has a divider by 5.
+ *
+ * There are formulas to get baud rate value for given input frequency and
+ * divider parameters, such as DDS_CLK_RATE and SCR:
+ *
+ * Fsys = 200MHz
+ *
+ * Fssp = Fsys * DDS_CLK_RATE / 2^24 (1)
+ * Baud rate = Fsclk = Fssp / (2 * (SCR + 1)) (2)
+ *
+ * DDS_CLK_RATE either 2^n or 2^n / 5.
+ * SCR is in range 0 .. 255
+ *
+ * Divisor = 5^i * 2^j * 2 * k
+ * i = [0, 1] i = 1 iff j = 0 or j > 3
+ * j = [0, 23] j = 0 iff i = 1
+ * k = [1, 256]
+ * Special case: j = 0, i = 1: Divisor = 2 / 5
+ *
+ * Accordingly to the specification the recommended values for DDS_CLK_RATE
+ * are:
+ * Case 1: 2^n, n = [0, 23]
+ * Case 2: 2^24 * 2 / 5 (0x666666)
+ * Case 3: less than or equal to 2^24 / 5 / 16 (0x33333)
+ *
+ * In all cases the lowest possible value is better.
+ *
+ * The function calculates parameters for all cases and chooses the one closest
+ * to the asked baud rate.
*/
-static u32 quark_x1000_set_clk_regvals(u32 rate, u32 *dds, u32 *clk_div)
+static unsigned int quark_x1000_get_clk_div(int rate, u32 *dds)
{
- unsigned int i;
-
- for (i = 0; i < ARRAY_SIZE(quark_spi_rate_table); i++) {
- if (rate >= quark_spi_rate_table[i].bitrate) {
- *dds = quark_spi_rate_table[i].dds_clk_rate;
- *clk_div = quark_spi_rate_table[i].clk_div;
- return quark_spi_rate_table[i].bitrate;
+ unsigned long xtal = 200000000;
+ unsigned long fref = xtal / 2; /* mandatory division by 2,
+ see (2) */
+ /* case 3 */
+ unsigned long fref1 = fref / 2; /* case 1 */
+ unsigned long fref2 = fref * 2 / 5; /* case 2 */
+ unsigned long scale;
+ unsigned long q, q1, q2;
+ long r, r1, r2;
+ u32 mul;
+
+ /* Case 1 */
+
+ /* Set initial value for DDS_CLK_RATE */
+ mul = (1 << 24) >> 1;
+
+ /* Calculate initial quot */
+ q1 = DIV_ROUND_CLOSEST(fref1, rate);
+
+ /* Scale q1 if it's too big */
+ if (q1 > 256) {
+ /* Scale q1 to range [1, 512] */
+ scale = fls_long(q1 - 1);
+ if (scale > 9) {
+ q1 >>= scale - 9;
+ mul >>= scale - 9;
}
+
+ /* Round the result if we have a remainder */
+ q1 += q1 & 1;
}
- *dds = quark_spi_rate_table[i-1].dds_clk_rate;
- *clk_div = quark_spi_rate_table[i-1].clk_div;
+ /* Decrease DDS_CLK_RATE as much as we can without loss in precision */
+ scale = __ffs(q1);
+ q1 >>= scale;
+ mul >>= scale;
+
+ /* Get the remainder */
+ r1 = abs(fref1 / (1 << (24 - fls_long(mul))) / q1 - rate);
+
+ /* Case 2 */
- return quark_spi_rate_table[i-1].bitrate;
+ q2 = DIV_ROUND_CLOSEST(fref2, rate);
+ r2 = abs(fref2 / q2 - rate);
+
+ /*
+ * Choose the best between two: less remainder we have the better. We
+ * can't go case 2 if q2 is greater than 256 since SCR register can
+ * hold only values 0 .. 255.
+ */
+ if (r2 >= r1 || q2 > 256) {
+ /* case 1 is better */
+ r = r1;
+ q = q1;
+ } else {
+ /* case 2 is better */
+ r = r2;
+ q = q2;
+ mul = (1 << 24) * 2 / 5;
+ }
+
+ /* Check case 3 only If the divisor is big enough */
+ if (fref / rate >= 80) {
+ u64 fssp;
+ u32 m;
+
+ /* Calculate initial quot */
+ q1 = DIV_ROUND_CLOSEST(fref, rate);
+ m = (1 << 24) / q1;
+
+ /* Get the remainder */
+ fssp = (u64)fref * m;
+ do_div(fssp, 1 << 24);
+ r1 = abs(fssp - rate);
+
+ /* Choose this one if it suits better */
+ if (r1 < r) {
+ /* case 3 is better */
+ q = 1;
+ mul = m;
+ }
+ }
+
+ *dds = mul;
+ return q - 1;
}
static unsigned int ssp_get_clk_div(struct driver_data *drv_data, int rate)
rate = min_t(int, ssp_clk, rate);
if (ssp->type == PXA25x_SSP || ssp->type == CE4100_SSP)
- return ((ssp_clk / (2 * rate) - 1) & 0xff) << 8;
+ return (ssp_clk / (2 * rate) - 1) & 0xff;
else
- return ((ssp_clk / rate - 1) & 0xfff) << 8;
+ return (ssp_clk / rate - 1) & 0xfff;
}
static unsigned int pxa2xx_ssp_get_clk_div(struct driver_data *drv_data,
struct chip_data *chip, int rate)
{
- u32 clk_div;
+ unsigned int clk_div;
switch (drv_data->ssp_type) {
case QUARK_X1000_SSP:
- quark_x1000_set_clk_regvals(rate, &chip->dds_rate, &clk_div);
- return clk_div << 8;
+ clk_div = quark_x1000_get_clk_div(rate, &chip->dds_rate);
+ break;
default:
- return ssp_get_clk_div(drv_data, rate);
+ clk_div = ssp_get_clk_div(drv_data, rate);
+ break;
}
+ return clk_div << 8;
}
static void pump_transfers(unsigned long data)
{
struct pxa2xx_spi_chip *chip_info = NULL;
struct chip_data *chip;
+ const struct lpss_config *config;
struct driver_data *drv_data = spi_master_get_devdata(spi->master);
unsigned int clk_div;
uint tx_thres, tx_hi_thres, rx_thres;
tx_hi_thres = 0;
rx_thres = RX_THRESH_QUARK_X1000_DFLT;
break;
- case LPSS_SSP:
- tx_thres = LPSS_TX_LOTHRESH_DFLT;
- tx_hi_thres = LPSS_TX_HITHRESH_DFLT;
- rx_thres = LPSS_RX_THRESH_DFLT;
+ case LPSS_LPT_SSP:
+ case LPSS_BYT_SSP:
+ config = lpss_get_config(drv_data);
+ tx_thres = config->tx_threshold_lo;
+ tx_hi_thres = config->tx_threshold_hi;
+ rx_thres = config->rx_threshold;
break;
default:
tx_thres = TX_THRESH_DFLT;
}
#ifdef CONFIG_ACPI
+
+static const struct acpi_device_id pxa2xx_spi_acpi_match[] = {
+ { "INT33C0", LPSS_LPT_SSP },
+ { "INT33C1", LPSS_LPT_SSP },
+ { "INT3430", LPSS_LPT_SSP },
+ { "INT3431", LPSS_LPT_SSP },
+ { "80860F0E", LPSS_BYT_SSP },
+ { "8086228E", LPSS_BYT_SSP },
+ { },
+};
+MODULE_DEVICE_TABLE(acpi, pxa2xx_spi_acpi_match);
+
static struct pxa2xx_spi_master *
pxa2xx_spi_acpi_get_pdata(struct platform_device *pdev)
{
struct acpi_device *adev;
struct ssp_device *ssp;
struct resource *res;
- int devid;
+ const struct acpi_device_id *id;
+ int devid, type;
if (!ACPI_HANDLE(&pdev->dev) ||
acpi_bus_get_device(ACPI_HANDLE(&pdev->dev), &adev))
return NULL;
+ id = acpi_match_device(pdev->dev.driver->acpi_match_table, &pdev->dev);
+ if (id)
+ type = (int)id->driver_data;
+ else
+ return NULL;
+
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return NULL;
ssp->clk = devm_clk_get(&pdev->dev, NULL);
ssp->irq = platform_get_irq(pdev, 0);
- ssp->type = LPSS_SSP;
+ ssp->type = type;
ssp->pdev = pdev;
ssp->port_id = -1;
return pdata;
}
-static struct acpi_device_id pxa2xx_spi_acpi_match[] = {
- { "INT33C0", 0 },
- { "INT33C1", 0 },
- { "INT3430", 0 },
- { "INT3431", 0 },
- { "80860F0E", 0 },
- { "8086228E", 0 },
- { },
-};
-MODULE_DEVICE_TABLE(acpi, pxa2xx_spi_acpi_match);
#else
static inline struct pxa2xx_spi_master *
pxa2xx_spi_acpi_get_pdata(struct platform_device *pdev)
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